RAG Files/Alzheimer's Disease - Diagnosis - 3.txt

The DSM-5 defines criteria for probable or possible Alzheimer's for both major and mild neurocognitive disorder.[120][121][110] Major or mild neurocognitive disorder must be present along with at least one cognitive deficit for a diagnosis of either probable or possible AD.[120][122] For major neurocognitive disorder due to Alzheimer's disease, probable Alzheimer's disease can be diagnosed if the individual has genetic evidence of Alzheimer's[123] or if two or more acquired cognitive deficits, and a functional disability that is not from another disorder, are present.[124] Otherwise, possible Alzheimer's disease can be diagnosed as the diagnosis follows an atypical route.[125] For mild neurocognitive disorder due to Alzheimer's, probable Alzheimer's disease can be diagnosed if there is genetic evidence, whereas possible Alzheimer's disease can be met if all of the following are present: no genetic evidence, decline in both learning and memory, two or more cognitive deficits, and a functional disability not from another disorder.[120][126]

The NIA-AA criteria are used mainly in research rather than in clinical assessments.[127] They define Alzheimer's disease through three major stages: preclinical, mild cognitive impairment (MCI), and Alzheimer's dementia.[128][129] Diagnosis in the preclinical stage is complex and focuses on asymptomatic individuals;[129][130] the latter two stages describe individuals experiencing symptoms.[129] The core clinical criteria for MCI is used along with identification of biomarkers,[131] predominantly those for neuronal injury (mainly tau-related) and amyloid beta deposition.[127][129] The core clinical criteria itself rests on the presence of cognitive impairment[129] without the presence of comorbidities.[132][133] The third stage is divided into probable and possible Alzheimer's disease dementia.[133] In probable Alzheimer's disease dementia there is steady impairment of cognition over time and a memory-related or non-memory-related cognitive dysfunction.[133] In possible Alzheimer's disease dementia, another causal disease such as cerebrovascular disease is present.[133]