Alzheimer disease

David S Geldmacher MD (

Dr. Geldmacher, Director of the Division of Memory Disorders and Behavioral Neurology at the University of Alabama at Birmingham, received research grants from Abbvie, Biogen, BristolMyersSquibb, Eisai, Janssen, Lilly, Lundbeck, and Neurim Pharmaceuticals, and consultation fees from Axovant, Grifols, and GlaxoSmithKline.

Martin R Farlow MD, editor. (

Dr. Farlow of Indiana University received research grant support from AbbVie, Biogen, Boehringer Ingelheim, Eisai, Eli Lilly, Genentech, Roche, Novartis, Suven Life Sciences Ltd, and vTv Therapeutics; fees from Cerecin/Accera, Allergan, Avanir, AZ Therapies, Eli Lilly, Kyowa Kirin Pharma, Longeveron, Medavante, Merck, Neurotrope Biosciences, Proclara, Takeda, and vTv Therapeutics for consultancy, or advisory board/DSMB membership; licensing fees from Elan; and consulting fees from Cortexyme, Green Valley, Regenera, Samumed, Zhejiang Hisun Pharmaceuticals, Cognition Therapeutics, Danone, Eisai, and Otsuka.

Originally released June 27, 1994; last updated February 19, 2020; expires February 19, 2023


Alzheimer disease is the most common cause of dementia (known as major neurocognitive disorder in the Fifth Edition of the Diagnostic and Statistical Manual for Mental Disorders) among people over age 65 years. In this article, the author presents an overview of the disease including clinical manifestations, pathophysiology, etiology, and diagnostic workup. Also included is information on results from clinical trials of diet and exercise.

Key points


• Alzheimer disease is the most common cause of dementia.


Memory loss is the dominant feature in most patients, often accompanied by anomia, visuospatial deficits, and executive dysfunctions.


• Current anti-dementia drugs often reduce symptomatic decline rather than improve cognition.


• Apathy, depression, and agitation are frequent noncognitive symptoms.


• The usefulness of antipsychotic drugs for treatment of agitation is modest and limited by increased mortality risks; SSRIs may offer a better safety and efficacy profile than antipsychotics for agitation without psychosis.


• The prevalence of Alzheimer disease is rapidly increasing and is projected to continue to rise through the 2050s. This increase reflects an aging population as well as higher rates of diagnosis among affected individuals.

Historical note and terminology

Although cognitive decline in advanced age has been recognized throughout history, the understanding that it represents the result of specific disease states is more recent. In 1907 the German neurologist and pathologist Alois Alzheimer reported the case of a 56-year-old woman with progressive cognitive decline and behavior change associated with distinctive neuropathological features of senile plaques and neurofibrillary tangles (Alzheimer 1907). Although the term “Alzheimer disease” is often used synonymously with “dementia,” current theoretical frameworks distinguish the pathology of Alzheimer disease from the symptomatic expression, accounting for constructs like “preclinical Alzheimer disease” and “mild cognitive impairment due to Alzheimer disease.” For clarity and brevity in this article, “Alzheimer dementia” will be used to denote “dementia due to Alzheimer disease.”

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