Careful evaluation of individuals with symptoms of dementia is important because some causes of cognitive impairment are treatable or reversible. Potentially reversible conditions include depression, adverse drug reactions, metabolic changes, and nutritional deficiencies, etc.

There is no single clinical test that can be used to identify Alzheimer's. A comprehensive evaluation includes a complete health history, physical examination, neurological and mental status assessments, analysis of blood and urine, electrocardiogram, and possibly an imaging exam, such as CT or MRI. A patient's caregiver, family member, or close friend may also be able to provide useful information about the patient's mental status. While this type of evaluation may provide a diagnosis of possible or probable Alzheimer's with up to 90 percent accuracy, absolute confirmation requires examination of brain tissue at autopsy.