Further neurological examinations are crucial in the differential diagnosis of Alzheimer's disease and other diseases.[25] Interviews with family members are used in assessment; caregivers can supply important information on daily living abilities and on the decrease in the person's mental function.[137] A caregiver's viewpoint is particularly important, since a person with Alzheimer's disease is commonly unaware of their deficits.[138] Many times, families have difficulties in the detection of initial dementia symptoms and may not communicate accurate information to a physician.[139]

Supplemental testing can rule out other potentially treatable diagnoses and help avoid misdiagnoses.[140] Common supplemental tests include blood tests, thyroid function tests, as well as tests to assess vitamin B12 levels, rule out neurosyphilis and rule out metabolic problems (including tests for kidney function, electrolyte levels and for diabetes).[140] MRI or CT scans might also be used to rule out other potential causes of the symptoms – including tumors or strokes.[134] Delirium and depression can be common among individuals and are important to rule out.[141]