Early and careful evaluation is important because many conditions, including some that are treatable or reversible, can cause dementia. Potentially reversible conditions include depression, adverse drug reactions, metabolic changes and nutritional deficiencies.

There is no single clinical test to identify AD. A comprehensive evaluation to establish diagnosis will include a complete health history, physical examination, neurological and mental status assessments and other tests, including analysis of blood and urine, electrocardiogram (EKG) and chest x-rays. Documenting symptoms and behavior over time, in a diary fashion, will help physicians understand the person's illness.

The physician may order additional tests as needed including: computerized tomography (CT Scan), electroencephalography (EEG), formal psychiatric assessment, and/or neuropsychological testing. While this evaluation may provide a diagnosis of possible or probable AD, confirmation of AD requires examination of brain tissue which is usually done by an autopsy.