Abstract This article provides a comprehensive review of Alzheimer's disease, providing a description of the history, symptoms, causes, diagnosis, genetics, risk factors, treatment, and societal impact of the disease. Alzheimer's disease (AD) is characterized behaviorally by progressive memory and cognitive decline and physiologically by the presence of amyloid beta plaques and neurofibrillary tangles in the brain. The underlying cause of AD, as well as its treatment, is still under investigation. A number of valuable diagnostic tools have been developed and continue to be improved. Risk factors for AD include age, genetic predisposition, environmental factors, cardiovascular diseases, diabetes, and diet.