Nitric oxide is a ubiquitous signaling radical that influences critical body functions. Its importance in the cardiovascular system and the innate immune response to bacterial and viral infections has been extensively investigated. The overproduction of NO is an early component of viral infections, including those affecting the respiratory tract. The production of high levels of NO is due to the overexpression of NO biosynthesis by inducible NO synthase (iNOS), which is involved in viral clearance. The development of NO-based antiviral therapies, particularly gaseous NO inhalation and NO-donors, has proven to be an excellent antiviral therapeutic strategy. The aim of this review is to systematically examine the multiple research studies that have been carried out to elucidate the role of NO in viral infections and to comprehensively describe the NO-based antiviral strategies that have been developed thus far. Particular attention has been paid to the potential mechanisms of NO and its clinical use in the prevention and therapy of COVID-19. Unfortunately, the availability of effective antiviral drugs is limited. Although a great deal of effort has been devoted to the development of new therapeutic approaches since the first approval of an antiviral drug in 1963, only 90 drugs were formally approved up to 2016 [The enormous cost of viral infections has been made abundantly evident over the last two years, in which we have observed the worldwide spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which affects every aspect of human life and all economic sectors . After t to 2016 . Further to 2016 ,6, and i to 2016 . Its use to 2016 . The aimNO is a radical species that is involved in a variety of physiological and pathological processes. It is ubiquitous in mammalian tissues, where it is produced from the conversion of L-arginine into L-citrulline in a reaction catalyzed by three isoforms of the enzyme NO-synthase (NOS). The three isoforms differ in terms of the regulation, amplitude and duration of NO production, and their tissue localization . NeuronaNO has direct effects in that it can block the functions of target molecules by reacting with the metal centers . It also has indirect effects that are mediated by its reaction with oxygen and the superoxide anion to give reactive nitrogen species (RNS), which then oxidize, nitrate and nitrosate target molecules .The balance between the physiological and pathological effects of NO depends on its concentration, meaning that any proposal to use NO for therapeutic purposes should take its concentration and localization into careful consideration.S-nitroso-N-acetylpenicillamine (SNAP) was demonstrated to have in vitro activity against SARS-CoV-1 [While endogenous NO is one of the major mediators in the body’s defense against microorganisms in the airway, its antiviral role has been less extensively studied. The non-specific action that NO exerts against viruses was first described in the early 1990s, and, since these pioneering studies, further evidence has demonstrated that NO exerts an action against all types of viruses, including the coronavirus, with broad activity ,15. ReseRS-CoV-1 . SubsequRS-CoV-1 ,18. StudMany studies have shown that a number of diseases caused by viral infection are characterized by an increase in NO levels. Indeed, following infection, the large amounts of NO that are necessary to fight viruses are produced thanks to the upregulation of iNOS via the activation of several pathways that are mediated by: (i) toll-like receptors (TLRs); (ii) signal transducer and activator of transcription 1 (STAT-1); and, (iii) protein kinase-R (PKR) , as summiNOS activation results in the increased production of NO, which is effective against both DNA and RNA viruses, including SARS-CoV-2 . NO actiS-nitrosylation of the cysteine residues that are directly involved in catalysis or present near the active site [S-nitrosylation of the cysteine in the enzyme active site [(1) The inactivation of viral proteins via nitrosylation reduces or inhibits enzyme activity. Target proteins include proteases, reverse transcriptases, ribonucleotide reductases, transcription factors and tyrosine-containing enzymes . The mecive site . For SARive site . In factive site . Host prive site . Anotherive site .(2) Deamination of viral DNA following nitrosative stress. NO induces DNA damage both to viral and host genetic material, although host DNA can be repaired by the DNA repair machinery .(3) NO increases the clearance of pathogens, including DNA and RNA viruses, by enhancing ciliary beat frequency ,25. NO aThe high levels of NO produced following iNOS induction also play a role in the inflammatory response. Acute inflammation is a defense mechanism against pathogens and has the aim of destroying or inactivating the invading microorganisms. If microbes are killed and cellular debris removed, inflammation is resolved and the normal tissue is restored. However, when excessive and non-regulated inflammation persists, it leads to tissue damage. During sustained inflammation, NO is produced in high quantities and regulates the activity of a variety of inflammatory mediators, including NF-kB . Other eThe endothelial cells that line vessels control several vascular functions, including blood flow, blood fluidity and vascular permeability. For an in-depth description, see the review by Pober and Sessa .The vascular endothelium acts in response to changes in the microenvironment  and induces the release of specific mediators that act in the control of the tone of smooth muscle cells . These m2+ concentration and mediators such as acetylcholine and bradykinin [Under physiological conditions, the maintenance of blood fluidity, via the inhibition of coagulation is another role of the vascular endothelium . NO alsoadykinin . NO workadykinin .Impaired endothelial function, with reduced NO availability, is found in diseases such as diabetes mellitus, obesity and hypertension . The redThe maintenance of endothelium functionality is essential as it allows for controlled exchanges between blood and the surrounding tissue and corrects vascular tone, while also avoiding the formation of a pro-thrombotic environment. Alterations in the vascular endothelium are therefore associated with pathological conditions, such as those related to viral infections. HIV infection is associated with oxidative stress, which reduces NO availability, leading to endothelium dysfunctions . Similar2+-dependent K+ channels [NO is produced in the human airway by the three isoforms of NOS . A reducchannels  and the channels .S-nitrosylation of surfactant proteins can induce a conformational change, leading to inflammatory response [Another factor in the respiratory system is the lung surfactant, a complex of proteins and phospholipids with the function of reducing surface tension at the air/liquid interface: evidence suggests a role for NO in surfactant secretion and the preservation of its function . At low response .iNOS, which is constitutively expressed in the airway epithelium, also contributes to the production of NO, which, among other functions, helps the regulation of ciliary beat, a defense mechanism of airway epithelium . The effThe use of NO in the treatment of pulmonary diseases is derived from this evidence .Although the role of NO in inhibiting viral replication in host defense has been demonstrated, NO-based antiviral strategies have not yet been extensively investigated. To date, no systematic approach has been adopted for the study of NO-based antiviral therapeutics, apart from those active in the cardiovascular system ,47. DespNO-based antiviral strategies can be mainly classified into two groups: gaseous NO (gNO) inhalation-based therapies and NO-donors. As well as chronic inflammatory diseases, viral infections of the upper respiratory tract are related to the presence of higher levels of NO in the air exhaled by human subjects. This is due to an increase in NO production as part of the host response to infection , with thTM; the recommended dosage was 20 ppm and the length of treatment was up to two weeks.The greatest efficacy found in gNO therapy to date has been demonstrated in the treatment of oxygen desaturation in infants with hypoxic respiratory failure. The treatment has been approved as a drug by the FDA under the trade name INOMAXIn the antiviral field, gNO inhalation-based therapies have resulted in quite discordant data, with one of the reasons for this being the gNO dosage sensitivity threshold. This limitation has been highlighted in gNO treatments following acute respiratory distress syndrome (ARDS), which is a particular pathological condition with a number of different etiologies such as SARS-related coronavirus infection (SARS-CoV), pulmonary ischemia-reperfusion (I/R) injury and bacterial/viral pneumonia. The role of NO in animal and human subjects affected by ARDS has been described in a work by Chen et al. .In a Beijing rescue study of fourteen patients with ARDS, which manifested as a result of SARS-CoV infection, gNO-based treatments performed for at least three days at a dosage of 30 ppm led to a marked improvement in arterial oxygenation in patients and a concomitant decrease in pneumonia infiltrates . On the Although the dosage of gNO in antiviral treatments must be significantly higher than in other applications, e.g., antimicrobial treatment ,66,70,71Other discrepancies in gNO inhalation-based antiviral therapies have been identified in dosage and the dependence of the therapeutic efficacy on the mode of gNO replenishment. In the antimicrobial field, Hall et al. observed a huge gap in the dosage between gNO and a soluble NO-releasing chitosan oligosaccharide . In otheN-diazeniumdiolates and S-nitrosothiols (RSNOs). Their general chemical structures are reported in There are three classes of NO-donors with antiviral effects; nitrites, N-diazeniumdiolates class and that has antiviral effects in Human Papillomavirus (HPV) raft cultures [NVN1000  d, which cultures , also dicultures ,53,76.SNAP e, a deriS-nitrosoglutathione (GSNO), have been incorporated into polymeric platforms [Several NO-donors, including SNAP and latforms ,81,82. Tlatforms ,84. The latforms ,86,87,88Endogenous NO-regulating drugs may be considered another potential class of antiviral drugs. These derivatives are described separately from gNO inhalation and NO-donors because of several discordances in the data collected in the literature. Reducing endogenous NO production is undoubtedly a therapeutic antiviral strategy and can be achieved by modulating iNOS activity. Pyrazole derivatives are examples of selective iNOS inhibitors that are active against the vaccinia virus ,90,91; cAlready-known drugs, such as ribavirin g have beNot always regulating iNOS activity in order to decrease endogenous NO production has led to the arrest of viral replication. In specific cases, instead of regressing, viral infection advanced if iNOS activity was downregulated. An example of this can be found in a study carried out by Santangelo et al. ; the virIn addition to these discrepancies, the use of drugs that can modulate iNOS activity has caused viral immunopathogenesis and, thus, the occurrence of numerous side effects . For thiCoronaviruses (CoVs) are a family of single-stranded positive-sense RNA viruses that contain a genome of approximately 30 kilobases and are named after their crown-like spike protrusions on the virus surface . After cBecause of the overlap of genetic structures and pathological features between SARS-CoV-1 and 2, knowledge of SARS-CoV-1 has provided suggestions for understanding SARS-CoV-2, including the role, potential mechanism and therapeutic application of NO. The promising results from the rescue trial during the SARS-CoV-1-caused epidemic in the years 2002–2004 , promptePathway 1—Although the main targets of SARS-CoV-2 are bronchial hair epithelial cells and type II lung cells, viral particles have also been found in endothelial cells. This is because SARS-CoV-2, SARS-CoV-1 and MERS-CoV lead to endothelial cell apoptosis with a consequent decrease in endothelial NO production [Pathway 2—SARS-CoV-2 invades host cells via the binding of its surface glycoprotein-S to angiotensin-converting enzyme 2 (ACE2) [Pathway 3—NO/ROS imbalance in the body triggers the considerable release of proinflammatory cytokines and chemokines, which lead to the overstimulation of the inflammatory system, causing significant damage to tissues and organs. In the meantime, ROS production, especially in the mitochondria, generates mitochondrial dysfunctions because of increased mitochondrial membrane permeability [Pathway 4—In order to restore the physiological ROS/NO balance, NO reacts with oxygen and its derivatives to form toxic reactive nitrogen species (RNS), such as peroxynitrite. The high concentration of ROS and RNS contributes to vascular oxidative stress, causing a change in vascular tones and leading to decreased NO bioavailability [There are four etiological pathways for COVID-19 that have been identified and described, and the level of endogenous NO and its bioavailability are quite low in each. oduction . Pathway2 (ACE2) . The dow2 (ACE2) ,106. Pateability . Pathwaylability . TherefoOn the basis of the outcomes obtained from the rescue clinical study following SARS-CoV-1 infection , gNO-bashttps://clinicaltrials.gov/ct2/show/NCT04305457), gNO is administered at 140–180 ppm concentration for 20–30 min, twice a day and for 14 consecutive days. The primary goal is to reduce the incidence of patients requiring intubation and mechanical ventilation, as a marker of deterioration from mild to severe COVID-19. The secondary goal is both the reduction of the mortality rate and the clinical recovery time. Clinical recovery means normalization of fever, respiratory rate, alleviation of cough and resolution of hypoxia. All these improvements must be maintained for 72 h. Other outcome measures are the increase in the percentage of patients with the negative conversion of RT-PCR from the oropharyngeal or oropharyngeal swab. The estimated study completion date is 1 April 2022.In the first clinical trial  is to investigate whether gNO treatment can improve oxygenation in mechanically ventilated patients. The treatment involves inhalation of 80 ppm nitric oxide for 48 h, followed by 40 ppm, followed by weaning before stopping. If a patient dies during the first 48 h of treatment, the last available blood gas analysis will be used. Secondary outcomes are the calculation of the time to reach normoxemia, the percentage of SARS-nCoV-2 free patients during the first 28 days after enrollment, and the survival rate both 28 days and 90 days after treatment. The estimated study completion date is 21 December 2022.The primary outcome of the second clinical trial  focuses on hospital-associated transmission among healthcare workers. 470 healthcare workers scheduled to work with COVID-19 patients were randomly selected and divided into two groups: the first received nitric oxide gas  while the second did not . The primary endpoint of this study is the incidence of subjects with COVID-19 disease 14 days after enrollment. Secondary endpoints are the percentage of caregivers presenting with a positive real-time RT-PCR test for SARS-CoV2 14 days after enrollment, the percentage of caregivers requiring quarantine, and the total number of days of quarantine in the two groups.The third clinical trial , which ended 30 June 2021, aimed to investigate whether gNO therapy could reduce both mechanical ventilator intervention and oxygen therapy use [The fourth clinical trial . Similarly, COViNOX is another NO-releasing drug that is in the third phase of clinical trials. In this trial, subjects were treated by means of an INOpulse device using an INOpulse nasal cannula .To overcome the use of gNO therapy, Kalytera Therapeutics Inc. announced, on June 29, 2020, that it has entered into a binding Letter of Intent to license R-107 from the Salzman Group for the treatment of CoVs and COVID-19 infection. R-107 is a non-gaseous, liquid prodrug of NO. Following a single administration by injection, R-107 slowly releases NO into the lung tissues over 48 h (17 February 2022, SNAP e has beeDespite decades of studies, fighting viral infections is still a great medical challenge, as the SARS-CoV-2 spread has recently demonstrated. Since the discovery of NO, many studies have described its role on the respiratory system, even if some aspects still need clarification. NO improves oxygenation, regulates lung vasculature and surfactant function, improves ciliary motility and is involved in host defense.As the role of NO in the defense against viral infections is becoming clearer and a positive role for this radical has been proposed in the treatment of respiratory infections, progress has been made in the development of NO-based therapies. gNO and NO-donors have been studied and some treatments have already been commercialized or are in ongoing clinical trials. Indeed, it should be considered that, depending on the concentration, NO can induce nitrosative stress and damage also host tissues.In the case of gNO therapy, more studies are needed to define the amount of the radical that is able to reach the local tissues in order to maximize clinical outcomes while reducing the potential side effects. In the case of NO-donors, the use of nanosystems is a particularly promising field as it allows drug delivery and targeting to be improved. For this reason, further studies are important as they can contribute to the development of innovative therapeutic approaches.


Anxiety disorders rank among the most prevalent mental disorders worldwide. Anxiety symptoms are typically evaluated using self-assessment surveys or interview-based assessment methods conducted by clinicians, which can be subjective, time-consuming, and challenging to repeat. Therefore, there is an increasing demand for using technologies capable of providing objective and early detection of anxiety. Wearable artificial intelligence (AI), the combination of AI technology and wearable devices, has been widely used to detect and predict anxiety disorders automatically, objectively, and more efficiently.This systematic review and meta-analysis aims to assess the performance of wearable AI in detecting and predicting anxiety.Relevant studies were retrieved by searching 8 electronic databases and backward and forward reference list checking. In total, 2 reviewers independently carried out study selection, data extraction, and risk-of-bias assessment. The included studies were assessed for risk of bias using a modified version of the Quality Assessment of Diagnostic Accuracy Studies–Revised. Evidence was synthesized using a narrative  and statistical  approach as appropriate.Of the 918 records identified, 21 (2.3%) were included in this review. A meta-analysis of results from 81% (17/21) of the studies revealed a pooled mean accuracy of 0.82 (95% CI 0.71-0.89). Meta-analyses of results from 48% (10/21) of the studies showed a pooled mean sensitivity of 0.79 (95% CI 0.57-0.91) and a pooled mean specificity of 0.92 (95% CI 0.68-0.98). Subgroup analyses demonstrated that the performance of wearable AI was not moderated by algorithms, aims of AI, wearable devices used, status of wearable devices, data types, data sources, reference standards, and validation methods.Although wearable AI has the potential to detect anxiety, it is not yet advanced enough for clinical use. Until further evidence shows an ideal performance of wearable AI, it should be used along with other clinical assessments. Wearable device companies need to develop devices that can promptly detect anxiety and identify specific time points during the day when anxiety levels are high. Further research is needed to differentiate types of anxiety, compare the performance of different wearable devices, and investigate the impact of the combination of wearable device data and neuroimaging data on the performance of wearable AI.PROSPERO CRD42023387560; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=387560 Anxiety is defined as an unpleasant emotional state whose cause is either not easily defined or considered to be uncontrollable or unavoidable, resulting in tension and physiological manifestations . AnxietyThe diagnosis of ADs is a very complicated and challenging task. Currently, ADs are diagnosed and screened primarily through clinical observations of patients’ mental states, clinical histories, and self-report questionnaires  for anxiety . HoweverAdvances in digital technologies and wireless sensors have led to the proliferation of wearable health care devices, which can be particularly useful for the diagnosis and prediction of anxiety. Wearable devices offer a convenient way for people with anxiety to monitor, examine, track, and share their health features, such as physical activities, heart rates, sleep patterns, blood oxygen, and respiratory rate. Wearable devices are made in different forms to meet their use requirements and can be classified into 4 types: on-body devices (fixed directly on the body or skin), near-body devices (fixed close to the body with no direct contact with the body or skin), in-body devices (implantable electronics), and electronic textiles (textiles with integrated electronics).Wearable devices have undergone a significant transformation over the last few years, reflecting the rapid advancement of technology in the field. Early iterations of smartwatches and activity trackers were primarily focused on basic monitoring and display functions. Many of these devices lacked connectivity options, limiting their ability to interact with other technologies. However, the introduction of Bluetooth components marked a turning point in the evolution of wearables, allowing for synchronization with smartphones and other wireless devices. This integration not only enhanced the user experience but also paved the way for more advanced functionalities.wearable AI technology. Wearable AI is the fusion of data obtained from wearables and sophisticated machine learning algorithms [More recent versions of wearable devices have embraced cutting-edge innovations by incorporating artificial intelligence (AI) and machine learning components, thus introducing what we call gorithms . Machinegorithms -16. If eIn the past few years, numerous studies have examined the performance of wearable AI devices for the detection of anxiety. In an effort to summarize these studies, several reviews have been conducted, but they had the following limitations. First, most extant reviews have largely focused on general wearable devices rather than wearable AI devices ,17-21. SThe authors conducted and reported this systematic review in accordance with the PRISMA-DTA  . The PRITo find relevant studies, the first author searched the following 8 electronic databases on October 3, 2022: MEDLINE (via Ovid), Embase (via Ovid), PsycINFO (via Ovid), CINAHL (via EBSCO), ACM Digital Library, Scopus, IEEE Xplore, and Google Scholar. An automated search was set up with biweekly alerts for 3 months . Owing to the large number of results retrieved from Google Scholar, only the first 100 hits  were checked for this review. To identify additional studies, we screened the reference lists of the included studies  and reviewed studies that cited the included studies .artificial intelligence, machine learning, and deep learning), those related to wearable devices , and those related to anxiety . The search queries used in this review are presented in The search terms used in this review were compiled after consulting with 3 experts in digital mental health and after reviewing relevant reviews. The search query was composed of 3 groups of terms: those related to AI . We excluded studies that used AI to predict the outcome of an anxiety intervention or treatment. The data acquisition had to be via noninvasive on-body wearables, such as smartwatches, smart glasses, smart wristbands, smart clothes, and smart rings. We excluded studies that used the following devices to collect the data: nonwearable devices, handheld devices , near-body wearable devices , in-body wearable devices , wearable devices wired to nonwearable devices, and wearable devices requiring expert supervision . This review included studies that collected data using other methods  along with wearable devices. We included peer-reviewed journal articles, conference papers, and dissertations with full text regardless of study settings, reference standards, and the country in which the study was conducted. Considering our focus on modern technology and the fact that the domain of wearable AI devices is under constant development, only articles from 2015 onward were included. Studies published in a language other than English or structured as review articles, editorials, conference abstracts, preprints, posters, protocols, and research highlights were excluded. Articles demonstrating a theoretical foundation for wearable AI devices for anxiety were disregarded.Relevant studies were identified through the following 3 steps. First, all the retrieved studies were imported into EndNote X9  to identify and eliminate duplicate items. Second, 2 reviewers independently screened the titles and abstracts of all the retrieved studies. Finally, the remaining articles were subsequently sourced in full text and inspected by the 2 reviewers independently. Any disagreements in the second and third steps were resolved through discussion. The Cohen κ was used to calculate interrater agreement, which was 0.90 for title and abstract screening and 0.94 for full-text reading.Using Excel (Microsoft Corp), 2 reviewers independently extracted metadata, wearable devices, AI algorithms, and results of the studies. The data extraction form used in this review was pilot-tested with 5 studies . Any disTo carefully assess the quality of the included studies, we adapted a well-known tool   for our meta package in R  [Narrative and statistical approaches were used to synthesize the data extracted from the included studies. In our narrative synthesis, we used text and tables to summarize and describe the characteristics of the included studies . With regard to the statistical approach, DerSimonian-Laird random-effects models  using thmputing) .metafor package in R (version 4.2.2) [In this review, some studies reported multiple effect sizes. Such studies will have a larger effect on the results of the meta-analysis than studies reporting only one effect size. Therefore, we used a multilevel meta-analysis ,31 to acn 4.2.2) .P value of <.05.When applicable, subgroup multilevel meta-analyses were conducted to assess for a possible association between outcome measures and different moderators . TheQ statistic (P<.05 indicated heterogeneity), between-study variance was assessed using τ2, and the magnitude of between-study variation because of true difference in effect sizes rather than chance was assessed using I2 [I2 ranged from 0% to 40%, moderate when it ranged from 30% to 60%, substantial when it ranged from 50% to 90%, or considerable when it ranged from 75% to 100% [Between-study heterogeneity was assessed using the Cochran using I2 ,33. The  to 100% .The results of the systematic search are presented in The key characteristics of the studies included in the review are presented in Among the included studies, 8 different wearable devices were used. Approximately a quarter of all studies  did not indicate what type of wearable device they used. The most common wearable devices used were the Fitbit series , the Empatica series , and Muse  did not provide adequate information to identify whether an appropriate consecutive or random sample of eligible patients was used. Most of the included studies  avoided inappropriate exclusions. The number of patients in the subgroups was appropriately balanced across half  of the studies. A sufficient sample size was reported in 43% (9/21) of the studies, whereas there was no clear indication of whether a sufficient sample size was used in the remaining studies . Consequently, the risk of bias resulting from the “selection of participants” was rated as low in only half  of the studies . A low lAlmost all studies  described the AI models in detail. Most of the included studies  provided a clear description of the features (predictors) used in the models, and the features in nearly all studies  were assessed in the same way for all participants. In all the included studies , features were collected without knowledge of outcome data. Thus, the risk of bias owing to the “index test” was rated as low in most of the included studies  was assessed using appropriate tools in 81% (17/21) of the included studies. The outcome was defined in a similar way for all participants in almost all studies  and was determined without knowledge of predictor information in all studies . An adequate interval was used between the index test and the reference standard in most studies . Accordingly, the risk of bias because of the “reference standard” was low in 90% (19/21) of the studies . All theAll participants enrolled in the study were included in the data analysis in 62% (13/21) of the studies. In 90% (19/21) of the studies, the data preprocessing was carried out appropriately, and in 86% (18/21) of the studies, the breakdown of the training, validation, and test sets was adequate. In 71% (15/21) of the studies, suitable measures were used to evaluate the performance of the models. According to these judgments, 76% (16/21) of the studies had a low risk of bias in the “analysis” domain . MultimeMeta-analyses were carried out for the highest accuracy, sensitivity, and specificity. Furthermore, when applicable, subgroup meta-analyses were performed to assess the performance of wearable AI based on different AI algorithms, aims of AI, wearable devices used, status of wearable devices, data types, data sources, reference standards, and validation methods. The following sections present the aforementioned results.P<.001; I2=99.9%). P>.05) was found in the highest accuracy between subgroups in all groups.Wearable AI accuracy, which is the ability of the AI to correctly classify patients with and without anxiety, was examined in 81% (17/21) of the studies. From these investigations, we extracted 40 accuracy estimates as multiple algorithms were often assessed in a single study. The highest accuracies observed spanned 0.50 to 1.00. As displayed in P<.001; I2=99.9%). P>.05) in the highest sensitivity was revealed between subgroups in all groups.In 48% (10/21) of the studies, the sensitivity of wearable AI, referring to the AI’s capacity to accurately identify patients with anxiety, was examined. From these studies, we extracted 24 sensitivity estimates as many studies assessed sensitivity for more than one algorithm. The highest sensitivity in these studies ranged from 0.21 to 1.00. A meta-analysis of the 24 estimates, involving 97,794 participants from the 48% (10/21) of the studies, revealed a pooled mean sensitivity of 0.79 (95% CI 0.57-0.91), as displayed in P<.001; I2=100%). P>.05) was found in the highest specificity between subgroups in all groups.The specificity of wearable AI, which refers to the AI’s capacity to accurately identify patients without anxiety, was examined in 48% (10/21) of the studies. From these studies, we extracted 24 specificity estimates as many studies assessed specificity for more than one algorithm. The highest specificity observed spanned 0.52 to 1.00. As displayed in This review aimed to assess the performance of wearable AI in detecting and predicting anxiety. The results of our meta-analyses showed that wearable AI has a good but not optimal performance in detecting and predicting anxiety. To be more precise, the review revealed that wearable AI was able to correctly classify patients with and without anxiety in 81% of cases. Furthermore, we found that wearable AI has a slightly better performance in detecting individuals who do not have anxiety (92%) compared with those who do (79%). This may be attributed to the fact that the number of controls  was larger than the number of cases  in 78% (14/18) of the studies that reported the number of cases and controls. Therefore, the algorithms were trained on imbalanced data with more representation of control samples. This review also demonstrated that the performance of wearable AI was not moderated by algorithms, aims of AI, wearable devices used, status of wearable devices, data types, data sources, reference standards, and validation methods. This finding should be interpreted carefully given that the number of studies in most subgroup analyses was small (≥5).As mentioned earlier, no previous reviews have examined the performance of wearable AI in detecting or predicting anxiety. However, a recent systematic review investigated the performance of wearable AI in detecting or predicting depression . AlthougAlthough this review showed that wearable AI is a promising tool for diagnosing anxiety, wearable AI is not ready to be implemented in clinical practice for the following reasons: (1) its performance in detecting patients with anxiety is not optimal at present, (2) the sample size was small (≤100) in two-thirds of the studies , and (3) only 29% (6/21) of the studies were judged to have a low risk of bias in all domains. Consequently, it is advisable to use wearable AI in conjunction with other clinical assessments and diagnostic criteria  to detect and predict anxiety.None of the commercial wearable devices in this review had AI embedded into them to detect anxiety. Instead, AI was embedded in a host device  where the data collected by wearable devices were stored. Therefore, there is a need to develop wearable devices that can promptly identify and predict anxiety, similar to those that detect stress , and are also capable of identifying specific time points during the day when anxiety levels are high, which could help users and health care providers identify causes of anxiety. We expect that this scenario could materialize in the near future, particularly with the advancements in wearable technology and the development of new chips that augment computing power.The studies included in this review did not use neuroimaging data in addition to wearable device data to detect or predict anxiety. Neuroimaging can play an essential role in the diagnosis of anxiety by visualizing the brain and identifying structural or functional changes that may be associated with ADs -59. ThroMost studies  included in this review focused on the performance of wearable AI in identifying current anxiety status rather than forecasting the likelihood or severity of anxiety in the future. Predicting the occurrence of anxiety in the future is as important as or more important than detecting the current anxiety state as it can help develop and deliver more effective, timely, and personalized interventions. Thus, we encourage researchers to conduct additional investigations on the performance of wearable AI in predicting the occurrence of anxiety in the future.None of the studies included in this review assessed the performance of wearable AI in distinguishing anxiety from other mental health conditions  or distinguishing types of anxiety . Typically, clinical practitioners rely on intricate and error-prone diagnostic methods to differentiate between various patient groups rather than merely distinguishing them from healthy individuals. As a result, additional research is necessary to examine the performance of wearable AI in distinguishing different types of anxiety and distinguishing individuals with anxiety from those with other mental disorders that exhibit comparable signs and symptoms of anxiety.As previously stated, the sample size of two-thirds of the studies  was limited to ≤100 participants. This may have hindered the detection of potential variations in the efficacy of wearable AI technology in subgroup analyses. In addition, it may have restricted the use of certain algorithms that require a considerable amount of data to be trained and tested. We encourage researchers to undertake additional studies with larger sample sizes and extended durations to ensure adequate statistical power and enable the use of more sophisticated and efficient algorithms that require greater quantities of data.Although the included studies used some common wearables , they did not assess the performance of other common wearables such as Google Pixel Watch, Galaxy Watch, and Oura Ring. Furthermore, none of the included studies compared the performance of different wearable devices. Therefore, it is recommended that researchers evaluate the performance of other wearable devices and compare their efficacies.The discrepancy between the wearable AI accuracy in detecting individuals with and without anxiety highlights the need for refining the AI algorithms to improve their performance. This could involve gathering more diverse and representative data, refining feature selection, or implementing advanced techniques to enhance the detection of anxiety among users.There are many challenges associated with the integration of AI into wearable devices for mental disorders in general and ADs in particular. First, obtaining high-quality data is difficult with wearable technology owing to differences in spatial, temporal, and data resolution. This becomes more challenging when multiple devices have to be combined to collect multiple types of data to generate a comprehensive picture of the body. Therefore, the quality of wearable data should be emphasized to improve the performance of the algorithms. To achieve this, there is a need for more practical standards for wearable device development that are necessary to ensure the consistent measurement of different signals generated from wearable devices. Second, the presence of missing data, outliers, signal noise, and artifacts can also lead to large variations and inaccurate algorithms . For exaThe transition of wearable AI into existing clinical practice for anxiety detection and management is an intricate process that requires careful consideration. A robust framework must be devised that outlines how wearable AI technologies can complement traditional methods such as interviews, self-report surveys, and existing diagnostic criteria. Such an integration framework would involve validating AI algorithms using established clinical guidelines, ensuring data privacy and security compliance, training health care providers in the interpretation of AI-generated insights, and creating a clear protocol for incorporating these insights into patient care. The integration of wearable AI into existing practices could offer a more refined, real-time understanding of anxiety levels, allow for tailored interventions, and foster collaboration between health care providers and technology developers. Efforts toward these integrations could form a promising direction for future research and innovation, contributing to a more effective and patient-centric approach to anxiety management.t test and ANOVA based on their power spectral density. The highest accuracies of 94.9% and 92.74% using an RF classifier were achieved from the 2 and 4 levels in the power spectral density of the EEG recording, respectively. In a study carried out by Arsalan and Majid [F1-score of 92.27% and 92.13%, respectively.Recently, various studies have proposed statistical and AI approaches for wearable devices to study the effectiveness of various parameters and biosignals  in differentiating patients with ADs from healthy individuals ,63-66. And Majid , EEG datnd Majid -70. In and Majid , a consund Majid , a wearaThis review cannot comment on (1) the performance of wearable AI in diagnosing other mental disorders ; (2) the performance of wearable AI in managing anxiety or predicting outcomes of anxiety treatment; and (3) the performance of nonwearable devices, handheld devices, near-body wearable devices, in-body wearable devices, wearable devices connected to nonwearable devices using wires, and wearable devices that require an expert to be applied on users. This is because such disorders, outcomes, and wearable devices were beyond the scope of this review, thus limiting the generalizability of our findings to these contexts. In addition, the results of our meta-analyses are likely to be overestimated or underestimated for 2 reasons. First, it is probable that we overlooked some studies as our search was limited to research published in the English language from 2015 onward and we did not use terms related to types of anxiety . Second, several studies in this review were not included in the meta-analyses as they did not provide findings suitable for meta-analysis.Although wearable AI shows promise in detecting and predicting anxiety, it is not yet advanced enough to be used in clinical practice. As such, wearable AI should be used along with other clinical assessments and diagnostic criteria to provide a more comprehensive understanding of a patient’s condition until further evidence shows an ideal performance of wearable AI. Wearable device companies should develop devices that can promptly detect anxiety and identify specific time points during the day when anxiety levels are high. There is a need to investigate the effect of using a combination of wearable device data and neuroimaging data on the performance of wearable AI in detecting and predicting anxiety. In addition, further studies are needed to differentiate among types of anxiety and differentiate patients with anxiety from those with other mental disorders. We urge researchers to compare the performance of different wearable devices in detecting anxiety.


Trust is essential for establishing stable and fulfilling romantic relationships between partners. Development of trust, however, can be assumed to depend on many factors related to an individual's earlier experiences and relationship-related beliefs. This study aimed to investigate how adult attachment style , experiences about parents' divorce and breakdown of one's own romantic relationship, and relationship beliefs are related to the level of dyadic trust in romantic relationships.t-tests, Pearson correlations, regression analyses and mediation analyses.The present study included 131 Turkish undergraduate university students (55.7% women) from different faculties. The research instrument had questions about parents' and respondents' own relationship status, Dyadic Trust Scale (DTS), Experiences in Close Relationships Inventory-Revised (ECR-R), and Inventory of Close Relationship Beliefs (ICRB), in addition to background questions. The data were analyzed using descriptive statistics, Respondents whose parents had divorced or who had experienced a relationship breakdown had lower dyadic trust scores than those without these experiences. The trust scores correlated negatively with anxious and avoidant attachment styles and positively with relationship belief scales, although the correlations to “external factors” were not statistically significant. In regression analysis, anxious and avoidant attachment styles explained 42% and relationship beliefs 25% of the variance in trust. The only significant predictor among beliefs was “individuality.” Mediation analysis showed that the effects of anxious attachment style on trust were fully mediated by the relationship belief in “individuality.” The avoidant attachment style had a direct relationship to trust.The results show that anxious attachment style influences trust via relationship beliefs, while avoidant attachment style has a strong direct effect on trust as well as weaker effects via beliefs. The results are discussed in the context of Turkish culture and horizontal collectivism. Trust is a key factor in successful romantic relationships. Trust evolves throughout the various stages of dating, flirting, engagement, and marriage , experiences about parents' divorce and breakdown of one's own romantic relationship, and relationship beliefs influence the level of dyadic trust in romantic relationships. Since heterosexual romantic relationships are very much based on sex and gender roles, we expected that there might be differences between men and women in relationships between attachment, relationship beliefs and dyadic trust. We hypothesized the following relationships:Participants who had experienced parental divorce or had separated themselves from a close relationship would score lower in trust than those whose parents are married or who have not experienced a breakdown of a romantic relationship.An anxious and avoidant attachment style would have a negative relationship with interpersonal trust.Positive relationship beliefs would have a positive relationship with interpersonal trust.The effects of attachment style would be at least partly mediated by relationship beliefs, i.e., attachment style would influence the beliefs, which, in turn, would be related to interpersonal trust.*power . The estimated sample size was n=111. The sample consisted of 131 undergraduate students of various majors , of whom 55.7% were women. The participants were student volunteers who completed a 20-min survey during their class hour. The participants did not receive any benefit from participating in the study. Participants were informed of their rights to voluntary participation and the option to stop answering at any time.The sample size estimation was conducted with GEthical approval was obtained from the Near East University Ethical Committee and the University of Kyrenia Ethical Committee (protocol number: YDU/SB/2020/615).n = 105, 80.2%) were married to each other, 21 (16.0%) were divorced or living separately, and two (1.5%) were widows or single parents not having been married. Since the number of widows or single parents was low, they were excluded from the analysis related to parental relationship status. Most participants reported being in a romantic relationship , 46 (35.1%) reported being single because of a breakdown of a relationship, and 21 (16.0%) reported never having been in a romantic relationship.The demographic information form included questions about gender , age (full years), relationship status of the parents  and relationship status of the respondent . Most parents , developed by Fraley and Shaver , measureThe Inventory of Close Relationship Beliefs, developed by Fletcher and Kininmonth , measuret-tests, reliability statistics, correlations and regression analyses. JASP was used for mediation analysis.IBM SPSS 28.0 was used for calculating descriptive statistics, t-tests were used. The only hypothesis (H1) was that a gender difference occurs in the variable concerned.Since gender is an important factor in adult heterosexual relationships, gender differences were calculated for the two attachment styles, the four relationship belief scales, and the dyadic trust scores. The tests of gender differences were considered exploratory and therefore direction of gender differences was not specified; consequently, two-tailed t-tests for gender difference are presented in t-test values for gender differences. Men scored higher than women in anxious attachment style, while women scored higher on the individuality scale of the ICRB. Women seem to value individuality  in relationships more than men. No gender difference was found in the other variables.The descriptive statistics separately for men and women and t-test was employed to investigate the mean difference in trust between respondents with parents who had divorced or separated and those with parents who remained together. Respondents with married parents scored higher  on the Dyadic Trust Scale than those with divorced parents , t(22.93) = 2.46, p = 0.011, Cohen's d = 0.82. This suggests that experiencing parental divorce might be associated with reduced trust in relationships. However, it's essential to note that the sample size for respondents with divorced parents was small (n = 21), which limits the generalizability of the results. These results confirmed Hypothesis 1, that respondents having experienced parental divorce experienced less trust in relationships.An independent samples  = 9.82, p < 0.001, η2 = 0.13. Bonferroni corrected pairwise comparisons indicated that respondents in an ongoing relationship had higher trust scores  than both those who had ended a relationship , p < 0.001, and those who had never been in a romantic relationship , p = 0.019. There was no statistically significant difference in trust scores between respondents who had ended their relationship and those who had never been in one. These results suggest that positive experiences in a romantic relationship may bolster interpersonal trust. Moreover, it can be inferred that respondents who had never been in a romantic relationship based their trust responses on their beliefs about romantic relationships in general. These results confirmed Hypothesis 1, which posited that respondents who had experienced a relationship breakdown would have less trust in relationships. No hypothesis was formed about not having been in a romantic relationship and trust.In addition to parental divorce, respondents also provided information about their current relationship status, choosing from the options: no relationship, relationship ended, or in an ongoing romantic relationship. A one-way ANOVA revealed a statistically significant main effect of relationship status, FCorrelations among study variables are displayed in p < 0.001) direct effect of avoidant attachment style on trust, whereas the direct effect of anxious attachment style on trust was not statistically significant (p = 0.054). The indirect effect of anxiety on trust via individuality was statistically significant . Similarly, the indirect effect of avoidance on trust via individualism was statistically significant . The total effects of both anxiety  and avoidance  on trust were statistically significant. The model explained 46% of the variance in trust scores.Hypothesis 4 proposed that the effects of attachment style on dyadic trust would be at least partly mediated by relationship beliefs. Consequently, The mediation model results show that the effects of anxious attachment on trust were fully mediated by individuality, whereas the direct effect of avoidant attachment style on trust was stronger than the mediation effect of individuality. We can, therefore, conclude that Hypothesis 4 was confirmed.When evaluating the results of the mediation analysis, it should be borne in mind that these analyses are based on a theoretical model, and no causal relationships can be confirmed based on cross-sectional data.This study aimed to investigate how attachment style , experiences about parents' divorce and breakdown of one's own romantic relationship, and relationship beliefs are related to the level of dyadic trust in romantic relationships. The findings were consistent with previous research showing that experiencing one's own relationship breakdown , demonstrated more conventional perspectives compared to their counterparts from less conservative locales and those with less vertical collectivism tendencies (Bugday et al., The mediation model indicated that the path from anxious attachment style to trust was fully mediated by individuality, while the direct relationship from avoidant attachment style to trust was stronger than the mediated relationship. An anxious attachment style reduces the belief in individuality and, hence, leads to lower trust. It seems that people with anxious attachment styles perceive a romantic partner's need for independence as a threat to the relationship. Avoidance is directly related to lower trust because, for an avoidant person, trust is simply not important in the relationship. In this manner, the mediation model illustrates two distinct pathways through which attachment style is related to trust.The study has some limitations. Firstly, it was based on volunteer participation. This might lead to self-selection bias, whereby participants scoring high in avoidant attachment style might also avoid participating. However, since the study was conducted during class hours and not online, the potential for self-selection bias should be less than in internet-based studies. Moreover, the issue of self-selection is inherent in all attachment studies based on self-reports, as participation in psychological studies must always be voluntary. In addition to possible self-selection, it should be noted that attachment in adult romantic relationships might be lower that the attachment theory suggests (Fraley et al., This study offers a preliminary examination of the mechanisms by which anxious and avoidant attachment styles may influence dyadic trust through relationship beliefs. It is noteworthy that beliefs about independence seem to play a pivotal role in dyadic trust, with these beliefs holding different degrees of importance for men and women. This observation, which might be particularly relevant for Turkish and other semi-collectivistic cultures, has profound implications for couple therapists and counselors. Divergent views between spouses regarding a woman's role and equality within relationships can lead to reduced trust, heightened emotional and behavioral jealousy, and, tragically, to relationship breakdowns and instances of domestic violence. As such, our initial findings should catalyze further extensive research and alert family therapists and couple counselors to this issue. If independence proves to be a cornerstone in building dyadic trust, it is imperative to communicate this insight to the broader public. Fostering mutual understanding between partners about a woman's role in marriage might enhance trust and overall relationship quality, especially in societies where collectivistic perspectives on marriage and relationships prevail.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving humans were approved by Near East University Ethical Committee and the University of Kyrenia Ethical Committee. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.TL: Conceptualization, Formal analysis, Methodology, Writing—review & editing. CDY: Conceptualization, Data curation, Investigation, Methodology, Writing—original draft. MJMS: Writing—review & editing.


Epigenetics studies the impact of environmental and behavioral factors on stable phenotypic changes; however, the state of the science examining epigenomic mechanisms of regulation related to secondary health conditions (SHCs) and neuroepigenetics in chronic spinal cord injury (SCI) remain markedly underdeveloped.This scoping review seeks to understand the state of the science in epigenetics and secondary complications following SCI.A literature search was conducted, yielding 277 articles. The inclusion criteria were articles (1) investigating SCI and (2) examining epigenetic regulation as part of the study methodology. A total of 23 articles were selected for final inclusion.Of the 23 articles 52% focused on histone modification, while 26% focused on DNA methylation. One study had a human sample, while the majority sampled rats and mice. Primarily, studies examined regeneration, with only one study looking at clinically relevant SHC, such as neuropathic pain.The findings of this scoping review offer exciting insights into epigenetic and neuroepigenetic application in SCI research. Several key genes, proteins, and pathways emerged across studies, suggesting the critical role of epigenetic regulation in biological processes. This review reinforced the dearth of studies that leverage epigenetic methods to identify prognostic biomarkers in SHCs. Preclinical models of SCI were genotypically and phenotypically similar, which is not reflective of the heterogeneity found in the clinical population of persons with SCI. There is a need to develop better preclinical models and more studies that examine the role of genomics and epigenomics in understanding the diverse health outcomes associated with traumatic SCI. Clinical Relevance: Identification of the mechanisms and relevant prognostic biomarkers that regulate the epigenome can support the development of targeted clinical decision making tools, and interventions. This article highlights the need to advance translational and precision applications in SCI research, bringing personalized care into the clinical environment. The SCI population is highly heterogenous in both American Injury Scale (AIS) level and the extent of permanent neurologic deficit. No two patients will have an identical pathophysiologic progression or clinical course post injury. However, functional recovery continues to be hampered by a paucity of clinical treatment options. Regenerative approaches are ongoing with small progress; treatment strategies remain exploratory, and few have translated to patients (T2), practice(T3), or community (T4) on the translational research spectrum. Post-injury management of secondary health conditions (SHCs) and complications is the key to longevity with good health and acceptable quality of life.Spinal cord injury (SCI) is a devastating condition that often yields permanent disability and challenges in medical care and symptom management. This once “ailment to not be treated” has over the years seen increased life expectancy resulting from advances in adaptive technology, pharmacologic intervention, and more robust understanding of SCI pathophysiology. The literature lacks consensus on how chronicity is defined likely due to the interindividual differences in functional recovery between human and preclinical pathophysiology. Thus, for the current review, we define chronicity as starting between 6 months to 1 year following injury.There are 3 generally accepted phases of recovery following traumatic SCI: (1) acute (hours to days), (2) subacute (weeks to months), and (3) chronic (>1 year) states. However, it is also accepted that more than 6 months post-injury is also considered chronic and may be more commonly reflected in preclinical studies. This is likely to be due to the interest in time-dependent inflammatory and immune responses post trauma. There is also increasing recognition that the long-term impact of traumatic SCI may be characterized as a sub-clinical inflammatory disease. A review by Noller and colleagues discussed the contribution of persistent chronic inflammation in SCI resulting in common SHCs. Chronic inflammation is significant for individuals living with SCI because of the increased risk of cardiometabolic disorders that are the leading cause of morbidity and mortality in this population. Several researchers have shown SCI-specific inflammatory and structural markers found in the blood/cerebrospinal fluid (CSF) linked to injury and neurologic loss may be predictive of functional recovery in SCI.10It has been found that most of the research on SCI has focused on acute and chronic phases.12 Disruption of gene expression patterns governed by hyper, or hypo methylation may result in autoimmune diseases, cancers, and various other illnesses, in contrast to genetic changes, which are difficult to reverse. However, environmental  influences on DNA methylation may be reversed if reduced or eliminated , and pharmaceutical interventions have also been used to reverse effects.16 The field of epigenetic research seeks to discover how lived environment, social condition, psychosocial factors, and nutrition affect an individual’s expression of genetic information. The 3 central mechanisms regulating epigenetics are (a) alteration of histone modification, (b) DNA methylation (DNAm), and (c) RNA regulation.Epigenetics is broadly defined as processes that may regulate gene expression and do not involve changes to the underlying DNA sequence: a change in phenotype without a change in genotype. However, the central regulating mechanisms remain the same. As more is being understood about environmental influences on disease development, multimorbidity, and health outcomes, epigenetic methodology opens the door to leverage biological and clinical data to inform SHC phenotypes in persons with SCI. Hence, to better understand the evolving science of epigenetics and its application in SCI research, we conducted a scoping review.Neuroepigenetics is distinguished from classic epigenetics due to its specific application to neurons, which means modifications are not propagated to progeny cells as seen in non-neuronal cells. A scoping approach was chosen to guide this review to map and characterize studies investigating epigenetic regulation and their links to SHCs after acute and chronic SCI. We hypothesize that given the paucity of literature on this topic, the influence of epigenetics remains an understudied area for this population. The specific purpose of this scoping review was to examine the state of the science focusing on epigenetics that attempts to explain SHC and other conditions associated with chronic SCI.Scoping reviews differ from systematic reviews in that they do not aim to produce a critically appraised and synthesized result/answer to a particular question, but rather focus on (1) identifying certain characteristics/concepts in papers or studies and (2) mapping, reporting, or discussing these characteristics/concepts.A librarian-assisted literature search was conducted across 4 databases  using the search terms “spinal cord injury,” “spinal cord injuries,” “epigenetics,” “epigenome,” “histone modification,” and “chromatin modification.” An Endnote library was shared with 277 articles from the years 2010 to 2020.LYG, T-FW), and 135 studies were retained for full text review. Three reviewers completed the full text review and final article abstraction . One author served to resolve conflicts if they arose (author LYG). After the removal of articles that did not meet inclusion criteria, a total of 23 articles was selected for final inclusion  was used to facilitate abstract and full text review. For inclusion, articles (1) investigated SCI and (2) examined a mechanism of epigenetic regulation as part of the study methodology. Articles were further excluded if they were reviews, commentaries, book chapters, or unavailable in English. Articles were uploaded to the Covidence software, and 30 duplicates were removed, resulting in 247 articles remaining for title and abstract review. Two reviewers completed the abstract review  and 9% using RNA regulation as epigenetic mechanisms. The studies occurred with mice (43%) and rats (44%) as the most commonly studied species. Only one human study was identified in this review. Most of the studies focused primarily on central nervous system (CNS) regeneration and plasticity, with only one article considered clinically relevant for SHC, such as neuropathic pain. We have divided and will discuss the included articles by epigenetic mechanism. Methyltransferase enzymes , are responsible for the transfer of the methyl group to DNA and are responsible for the mediation and maintenance of DNAm patterns  was used to analyze changes in folate receptor (Folr) expression, global methylation, and methyltransferase levels in wild-type and Folr knock-out adult male Sprague-Dawley rats and male mice. They found that injury-induced augmentation of Folr receptor expression is important to the regeneration effects of folic acid on the spinal cord. Changes in the Folr expression were related to the suppression of donor methyl groups to enable synthesis of S-adenosylmethionine (SAM), the primary donor in neurons and all cells of the CNS. DNA methyltransferases (Dnmts) were directly involved in the process via the methylation of hemi-methylated sites by Dnmt 1 and de novo methylation of previously unmethylated sites by Dnmt3a and Dnmt3b, resulting in detectable effects on suppressed Dnmt3a and Dnmt3b protein levels, returning to baseline following folic acid treatment. Global methylation decreased by 40% in the presence of injury (SCI) with the use of folic acid supplementation.In an earlier study by Iskandar et al used a contusion SCI model in adult male Sprague-Dawley rates to analyze the effect of folic acid on matrix metalloproteinase 2 (MMP2) expression and neuropathic pain. MMP2 is a protein coding gene found to be associated with diverse function, such as the induction of mitochondrial-nuclear stress signaling with activation of the pro-inflammatory NF-κB, NFAT, and IRF transcriptional pathways. They found that locomotor function improved among the folic-acid-treated group during mid and late phases of the injury, that is, comparable to subacute and chronic phases of SCI in humans, compared with the control (water) group. Moreover, those rats in the folic acid treatment group also demonstrated reduction in neuropathic pain compared to the control (water) group. In summary, folic acid and the folate pathway are mediated by epigenetic mechanisms. The use of folic acid supplementation appears to promote endogenous axonal regeneration and spinal cord healing.Miranpuri et al used Wistar rats to examine the role of abnormal DNAm in axonal regeneration and cell proliferation through histological observation, motor function assessment, and whole-genome bisulfate sequencing (WGBS) to detect gene methylation with Gene Ontology (GO) and KEGG pathway analyses. Histologically, they found several cavities, tissue necrosis, and glial scaring, with poor motor function in behavioral analysis. Bioinformatic analyses revealed 96 differentially methylated genes (DMG’s). Biological processes of the hypermethylated genes (50) were related to cell shape regulation and neurogenesis, while the biological processes enriched by the hypomethylated genes were related to brain development, protein phosphorylation, and ethanol response.Shi et al reported results of a bioinformatic analysis of data to identify common hypermethylated and demethylated genes from DNAm sequencing of samples taken before and after sciatic nerve injury in rats. Although the focus of this paper examined common DMG’s among SCI and non-CNS injury (sciatic nerve injury), one area of interest is identifying protein-protein interaction networks specific to SCI that may have shared pathways significant to SCI-related SHC. The findings of this study indicated 12 DMGs that are involved in biological regulation processes, such as cellular signaling and molecular functions of protein binding. Of particular interest was the Hippo signaling pathway given its activation by many demethylated genes important to neuroregeneration.Another study by Shi et al examined the perturbations of hydropymethylcytosine (5hmC), an oxidation product of DNAm, on gene expression related to cell death after SCI. In other neurological conditions such as TBI, stroke, and sporadic amyotrophic lateral sclerosis (ALS), 5hmC has been found to play an important role in ischemia and perfusion to the brain and spinal cord. A contusion SCI model was used in rats at the T9-T11, followed by quantitative real-time polymerase chain reaction analysis (qRT-PCR) and hydroxymethylated DNA immunoprecipitation (hMeDIP) assays. Results revealed that global change in DNA 5hmC levels significantly increased at 6, 12, and 24 hours after SCI. Additionally, gene expression changes were found to increase in the presence of ten-eleven translocation family (Tet2) enzyme and worsened SCI in the presence of SC-1, a Tet2 expression suppressor, suggesting the importance of 5hmC in the expression of genes related to cell death and survival in SCI and other neurologic conditions.Sun et al, Doherty et al focused on brain derived neurotrophic factor (BDNF), a known target of epigenetic modifications in the brain resulting from environmental influence. Male Sprague-Dawley pup rats underwent low-thoracic spinal cord transection and behavioral testing. This study was among the first to examine the epigenome of the developing spinal cord and the environmental influence on motor outcomes. The findings of this study support that SCI is linked to large increases in methylation throughout the spine.Lastly, DNAm was used to examine the developing spinal cord and its response to environmental input during locomotor development related to hindlimb activity.29 Six studies focused on histone acetylation, 6 examined histone deacetylation, and 3 examined histone demethylations. Histone acetylation is regulated by HAT and HDAC enzymes that add or remove acetyl groups to the N-terminal histone tails and together maintain acetylation homeostasis and play a role in plasticity transcription and regeneration-associated genes. Evidence demonstrates that downregulation of HDACs has positive effects on learning, memory, and synaptic plasticity. Seira and colleagues assessed the potential effect of trichostatin A (TSA), a known promotor of synaptic plasticity, neurogenesis, neuroprotection, and neurite branching in Pten knockout mice. They found that TSA had inhibitory effectors on HDAC, allowing for more acetylation and supporting axonal regeneration in young mice with Pten deletion.The bulk of the studies examined histone modification, the covalent, post-translational modification of histones. This epigenetic regulatory process impacts gene expression by altering chromatin structure  or recruiting histone modifiers, such as histone acetyltransferase (HAT), histone methyl transferase (HMT), histone deacetylase (HDAC), histone demethylase (HDMT), kinases, and E3-ubiquitin .28,29 Si measured glial fibrillary acidic protein (GFAP), S100 calcium-binding protein B (S100B), and global histone h4 levels in Wistar rats. They found that global histone H4 acetylation levels in the perilesional tissue are time-related after SCI, with the 72-hour (acute) timepoint revealing an increase in global histone H4 acetylation levels.De Menezes et al examined the influence of environmental enrichment versus standard housing (control) on Cbp-dependent histone acetylation-mediated axon regeneration. Enriched environment (EE) offers opportunities for increased motor, social, and sensory activity and has been found to enhance neural connections and improve functional recovery on behavioral testing.35 They found that by exposing mice to EE, cAMP-response element binding protein had a mediation effect on histone acetylation; thus, changes in chromatin that increase regenerative capacity of neurons result in increased sensory and motor functions.Hutson et al They examined the impact of a single body weight support gait training session on oxidative stress parameters, BDNF modulation, and global histone H3 and H4 acetylation levels in SCI participants. No changes were observed in BDNF levels, nor histone acetylation levels; however, there was an observed increase in levels of oxidative stress markers  in both treadmill and walker groups.The only human study in this scoping review was conducted by Goldhardt et al examined the role of bromodomain and extraterminal (BET) domain-containing proteins (epigenetic readers that bind acetylated lysines) on neuroinflammation after contusive SCI. The first finding was that BETs were expressed in all major CNS cell populations and their mRNA levels were not modulated in response to SCI. They also found that BET inhibition (via treatment with BET inhibitor JQ1) attenuated pro-inflammatory cytokine expression in activated primary CNS cells, astrocytes, oligodendrocytes, and microglia. Sánchez-Ventura et al also found that BET inhibition was effective in reducing pro-inflammatory cytokine production, promoting neuroprotection, and reducing acute neuropathic pain in a mouse contusion model.Rudman et al tested valproic acid (VPA), a known HDAC inhibitor, in rats after SCI. HDAC inhibition results in transcriptional reactivation by inducing histone acetylation through HDAC enzyme suppression. Their findings support earlier studies which also report neuroprotective effects of VPA and increased BDNF and GDNF mRNA levels in neurodegenerative conditions. Kim et al investigated changes in the expression of the main regulators of neuronal survival and death. Following contusion injury to young male mice, they found the upregulation of BDNF, GDNF, and HDAC1 expressions, with HDAC1 being an important regulator of neuron apoptosis. Another study of changes in the main regulators of neuronal development, survival, and death in a contusion SCI rat found similar results. Neurotrophic factors BDNF, NGG, GDNF, and HDAC1 were examined, and BDNF was found to be significantly elevated in the SCI group compared to the control, while the other factors were not found highly expressed. Although increased levels of HDACs were found to be expressed in the brain, their role in brain reorganization after injury remains poorly understood.Abdanipour et al examined class IIa HDACs, which differ from class I and class IIb HDACs by their sequence and structural organization, in that they rarely interact with histone tails or the removal of acetylated lysine groups. To better understand the epigenetic mechanism of macrophages , a male mice contusion model was tested with TMP269, a highly selective class IIa HDAC inhibitor. They found that the TMP269-treated group had higher levels of pro-inflammatory cytokines , suggesting the critical role of class IIa HDACs as powerful inhibitors of pro-inflammatory cytokines in macrophages. Sanchez et al specifically examined HDAC3. They hypothesized that HDAC3 inhibition suppresses the phenotype M1 (pro-inflammatory) and promotes the anti-inflammatory phenotype M2 to improve functional SCI recovery. By introducing scriptaid and RGFP966, known HDAC3 inhibitors to female mice with T-cut spinal cord hemisection injury, they found that histone 3 and 4 acetylation were increased, and macrophage polarization was skewed toward M2 phenotype (anti-inflammatory). Scriptaid treatment also decreased M1 macrophage foaminess, while RGFP966 significantly reduced the formation of foamy macrophages in both. They also found that foamy macrophages became proinflammatory and hindered regeneration. Taken together, HDAC inhibitors are strong targets for macrophage polarization and creating an anti-inflammatory environment for SCI recovery.Qi and Wang also studied HDAC3 to determine its role as a novel mechanism to discriminate between axonal regeneration and regenerative failure in dorsal root ganglia (DRG) sensory neurons. Conducting both in vivo and bioinformatic analysis, they found that reduced HDAC3 activity allowed for increased histone acetylation and regenerative gene expression in DRG. However, HDAC3 phosphorylation is calcium dependent and spinal injury does not induce the calcium-dependent protein phosphate 4 (PP4) activity needed for this process. The finding of both analyses supports the role of HDAC3 in restricting the regeneration program needed to enhance DRG neurite growth and expression of regeneration-associated genes including JUN, MYC, STAT3, ATF3, and FOS with key signaling pathways of MAPK, insulin, and JAK-STAT.Hervera et al46 and Ni et al investigated the epigenetic regulation of angiogenesis and vascular regeneration in SCI. The study of post-SCI vascular regeneration by Ni et al  examined mRNA levels of UTX, EZH2, Jmjd3, CBX8, CBX4, CBX6, and CBX7 at the site of the spinal lesion post-SCI contusion in C57BL/6J wild-type and UTX knockout male mice. They found that UTX was elevated at the day 3 timepoint and remained elevated at days 7 and 14 and was found to occur in CD31+ endothelial cells, implicating the potential role of UTX in vascular regeneration post SCI. They went on to demonstrate that UTX regulated expression of miR-24 (increased expression during myogenesis) by binding to the promoter and directly decreasing the level of methylation in several CpG positions in the miR-24 promoter, thereby promoting the expression of miR-24. In summary, UTX deletion can epigenetically promote vascular regeneration and functional recovery post SCI via a regulatory network with miR-24.Lee et al46 histone H3K27 demethylation Jmjd3 was characterized for its role in acute inflammatory response regulation. Lee et al used adult Sprague Dawley male rats subjected to T10 contusion. They found that Jmjd3 gene expression was increased within the first 8 hours after SCI and was more highly expressed in blood vessels at or near the injured spinal cord lesion site. This suggested that it is acutely upregulated following injury with specific functions in acute immune response and/or the blood-spinal cord barrier (BSCB). Moreover, given its role as a transcription activator through demethylation of trimethylated histone H3K27, it is also associated with inflammation-specific markers. The Lee et al study found that IL-6 showed a similar upregulation pattern as Jmjd3, which indicated that in the absence of Jmjd3, the upregulation of IL-6 is inhibited. Lastly, transcription activators known to bind to IL-6 gene promoters, such as NF-kB, were examined for interaction with Jmjd3 using both Western blot and chromatin immunoprecipitation (ChIP) assays. They found that Jmjd3 was directly involved in IL-6 gene activation by demethylation of H3K27me3 at the promoter in cooperation with NF-kB and C/EBP.In both Lee et al studies, contribute findings to the critical role of histone H3K27 demethylase Jmjd3 in the regulation of matrix metalloprotease (MMP) gene expression and BSCB integrity. MMP activation is known to contribute to permanent neurological disability after SCI because of blood cell infiltration, inflammation, and apoptosis.MMP-2, MMP-3, and MMP-9 are specifically known to be involved in SCI-induced BSCB disruption, but the mechanisms following SCI are not well understood. Again, using adult Sprague-Dawley male rats, SCI was induced using a contusion model at T9-T10. They found that Jmjd3 activated MMP-2, MMP-3, and MMP-9 expression in brain endothelial cells upon OGD/reperfusion injury. Using Jmjd3 siRNA to deplete the Jmjd3 transcript, they determined that depletion of Jmjd3 expression inhibited the upregulation of MMP-2, MMP-3, and MMP-9 expression and activities. Like their previous work that found NF-kB to be associated with Jmjd3 activation of IL-6 gene expression, they found in this study that NF-kB was also required for Jmjd3-mediated MMP-2, MMP-3, and MMP-9 gene activations. These 2 studies reinforce the significance of NF-kB involvement as a mediator of gene expression both in DNA methylation and histone demethylation. The combined results of all 3 studies provide potential therapeutic clues for targeting vascular regeneration in the treatment of SCI.Lee et al Using small interfering RNAs (siRNAs) to inhibit the interphase phase of the cell cycle, Wang et al studied epigenetic silencing of cyclinD1 in bone-marrow-derived mesenchymal stem cells (BMSCs) for protective effects in rats after SCI. Cyclins are proteins that function to progress the cell cycle by binding a group of enzymes called cyclin-dependent kinases (CDKs) which phosphorylate target proteins. CyclinD1 specifically is responsible for progressing the cell cycle from G1 to S phase. Inhibition of CyclinD1 expression is associated with downregulation of pro-inflammatory cytokines, which may be a potential therapeutic target for pro-inflammatory conditions such as SCI.miRNA is a class of non-coding small RNA that functions to downregulate gene expression through mRNA cleavage, translational inactivation, and deadenylation .16 UsiGFAP-positive and NGF-positive cells were significantly increased in the si-cyclinD1 + BMSCs and BMSC groups compared with the control group. GFAP and NGF regulation were associated with enhanced astrocyte proliferation. These findings, along with higher BBB scores in groups with si-CyclinD1-engineered BMSCs, support that by silencing CyclinD1, BMSC may promote functional recovery.In female Sprague Dawley rats, cyclinD1 was transplanted with BMSCs into the lesion area of the SCI using siRNA plasmids. CyclinD1 was found nominally expressed by Western blotting and qRT-PCR, confirming that siRNA transfection was successful. Observations of histological changes confirmed decreased tissue edema, inflammatory cell infiltration at the site of the SCI lesion, and smaller syrinx in groups with si-cyclinD1 + BMSCs and BMSC groups compared with the control and sham groups. Additionally,  sought to use bioinformatic analysis to construct and integrate ceRNA network of critical genes, miRNAs, long non-coding RNAs (lncRNA), transcription factors, and signaling pathways. Gene expression data sets were used from the gene expression omnibus (GEO) database to define the “SCI group” as mice with SCI acquired by contusion. DEG analysis was performed using GO and KEGG enrichment. They found 4 genes , 4 transcription factors , 2 miRNAs (miR-16-5p and miR-325-3p), and 3 lncRNAs  that are considered significant contributors to the pathogenesis of subacute SCI.In another study investigating the subacute phase of SCI, Wang et al  Current evidence suggests that in the presence of lost neuronal acetylation homeostasis, short- and long-term chromatin architecture changes, resulting in the development of neurodegenerative disorders, such as Parkinson’s disease (PD), multiple sclerosis (MS), stroke (CVA), and Alzheimer’s disease (AD), which has significance post-SCI neurodegenerative changes. Notably, the histone acetylation-deacetylation balance modulates different cell types, such as inflammatory and immunological cells, which influence the severity of blood-brain barrier dysfunction, axonal demyelination, oxidative stress, and injury impact.54 Applying neuroepigenetics to SCI research could lead to new approaches in rehabilitation where re-learning motor activities could improve functional outcomes.The results of this scoping review suggest that there is an increasing enthusiasm for epigenetics and neuroepigenetics in SCI research, especially given the increased complexity when considering the different cell types that exist in the brain and spine. Further, the findings from this review offer exciting insights into neural circuits and synaptic plasticity involved in learning new information. The emerging sub-discipline of neuroepigenetics describes the “discoveries of a wide variety of roles for epigenetic molecular mechanisms in the central nervous system (CNS) regarding acquired behaviors, CNS disorders, neural plasticity, neurotoxicity, and drug addiction.” presented the Rehabilomics research framework, offering a translational path for rehabilitation research that combines omics technology with personal biology, physiological responses to environmental exposures, and biopsychosocial outcomes based on the World Health Organization International Classification of Functioning, Disability, and Health domains. However, this adapted model primarily focuses its application on traumatic brain injury (TBI) research. While TBI and SCI share similarities in primary and secondary injury cascades following mechanical injury, the study of SCI and the chronic SHCs that follow remain understudied. Individuals living with SCI are living longer and have increased and/or unpredictable levels of risk for developing a wide range of SCI-driven SHCs. The identification and use of prognostic biomarkers are major steps in developing decision trees, predictive tools, personalized interventions, and treatments.This scoping review also reinforces the dearth of studies that examine the potential of clinically applied precision health within the rehabilitation setting, particularly for individuals living with SCI and managing SCI-associated SHCs. Many of the studies included in this review examined changes in the acute or subacute post-SCI phase. None of the studies looked at these gene expression changes in chronic SCI, thus leaving a larger gap in the significance of chronicity on these mechanisms. Understanding gene expression and its regulation translates to more accurate diagnosis and treatment for clinically significant changes in phenotype. Wagner These clinical features are reinforced by the findings of studies included in this scoping review, particularly as key genes, proteins, and pathways that were present in multiple studies, including brain derived neurotrophic factor (BDNF), glial cell derived neurotrophic factor (GDNF), neuronal growth factor (NGF), histone deacetylase 1 (HDAC1), NF-kappaB signaling pathway, and the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathways. These key genes and pathways offer an opportunity to develop our understanding of mechanisms underlying SCI-triggered SHC that result from gene expression activation and/or silencing.The subacute phase after SCI is categorized by neuronal apoptosis, axonal demyelination, Wallerian degeneration, axonal remodeling, and glial scar formation, while the chronic phase is characterized by cystic cavity, axonal dieback, and maturation of glial scar.BDNF is well known for its glucose and energy metabolism regulation, as well as neuroplasticity and synaptogenesis. The JAK-STAT pathway is an essential signaling pathway for several cellular response functions including inflammatory responses, hypoxia/reperfusion, cellular stress, and more. Saligan found that the BDNF Val66MET single nucleotide polymorphism (SNP) genotype was protective against cancer-related fatigue. This could be a significant target in the fatigue experienced by individuals living with SCI and chronic multimorbidity. BDNF is also implicated in stress-related phenotypes, which given its role in brain-based gene regulation, has implications for shared mechanisms of other stress-related conditions, such as depression and anxiety.GDNF is a protein coding gene specifically associated with SCI and is also involved in the RAF/MAP kinase cascade super pathway that, like JAK-STAT, regulates cellular processes related to differentiation, survival, senescence, and cell movement.60 has shown the genetic influence of candidate DNA variants and single nucleotide polymorphism (SNPs) on intramuscular adipose tissue (IMAT) accumulation and recurrent pressure injury (PrI) risk. They have previously shown that varying levels of circulatory biomarkers may be indicative of recurrent PrI risk.60 Furthermore, genetic biomarkers, specifically those related to fatty metabolism, are indicative of persons with SCI at highest risk for recurrent PrI. Histone H3K27me3 demethylase Jmjd3 has been found to be involved in wound repair and the inflammation process,63 highlighting the value of incorporating both genetic and epigenetic regulation of gene expression, as it may hold significance for the study of pressure injury and other SHCs after SCI. Thus, defining the epigenetic mechanisms linked to remodeling neural tissue would help researchers design therapeutic strategies to promote wound healing and tissue functionality after SCI among other potential targets.65Preliminary work by Bogie and colleagues, and recognizes the “complex relationships within and between symptoms both in a single chronic condition and among chronic conditions .” Symptoms serve as critical clues to changes in health status  and are the primary reason urgent or emergent care is sought, which may (or may not) lead to hospitalization and/or diagnosis of a newly developed SHC. This is of particular importance for SCI research, where individuals are likely to suffer higher rates of multimorbid SHCs and the management of accompanying symptoms.There is a key discussion absent in SCI research around epigenetics, chronic multimorbidity, and SHCs. Symptom science is “focused on quantifying subjective symptom experiences and measuring the biologic, physiologic, and omics underpinnings of symptoms and sequela common to health conditions and their treatments” While we present the effects of epigenetics leading to the development of multimorbid SHC, that is, the gene-environment, it is very probable that multimorbid SHC directly lead to remodeling in the epigenome. Studies looking at the influence of changes due SHC on the epigenome need to address the dynamic variability inherent in epigenetic studies. Prospective studies to measure and compare pre-multimorbidity states are also challenging. Multimorbidity as previously described carries a significant burden for individuals living with SCI and is influenced by age and injury characteristics . These influences also carry significant complexity in the presence of the injury. Although the relationship between multimorbid SHC and epigenetic change is even less understood given the dearth of research in this field, we wanted to acknowledge it as an important consideration as more work is being done to develop this field.Diseases can often be due to multiple factors including routine environmental exposures.72 Development of a Rehabilomics theoretical model specific to SCI symptomology would provide guidance that would support the translation of bench findings to clinical management of chronic multimorbidity resulting from SCI.Theoretical models have been developed to improve our understanding of the mechanisms that contribute to symptom behavior . However, symptom behavior and associated mechanisms has primarily been evaluated in other conditions, such as cancer and cardiovascular disease; only one study addresses symptom behavior in SCI research.This scoping review has revealed some key epigenetic regulators of gene expression and adjacent pathways that appear to overlap many critical biological, molecular, and cellular processes following SCI. However, it also elucidates the need for more translational/applied clinical research as a next step from the bench to begin impacting the patient. Given the paucity of research that studies the concepts of epigenetics, SHCs, and/or their associated symptoms in SCI research , more work in this area is critical to continue advancing our understanding of SCI-specific biobehavioral outcomes.