An overview of the etiology, diagnosis, and treatment of Alzheimer disease.

Alzheimer disease (AD) is the most common form of dementia affecting elderly people. It is the fourth leading cause of death among adults in the United States, following heart disease, cancer, and stroke. The prevalence of AD increases with increasing age. An estimated 10% of people aged 65 years have this progressive, degenerative disease, and this percentage increases to 47.2% for people aged 85 years and older. An early-onset form of AD can affect individuals who are middle-aged, with the youngest documented case being that of a 28-year-old. In the Framingham cohort, women with AD outnumbered men by a ratio of 2.8:1 for those aged 75 years or older. Undoubtedly, as our population continues to age, the increasing prevalence of AD will have an even greater impact on society than it does today. Approximately 4 million Americans have AD, and it is projected that the number will rise to 14 million by the middle of the next century. The financial impact of AD is staggering, with the average lifetime cost for an individual with AD exceeding $170,000. Although the majority of individuals with AD are cared for by family and friends at home, individuals with AD constitute half of all nursing home residents. The average cost of a year of nursing home care for an individual with AD is $42,000, and this cost can exceed $70,000. The purpose of this article is to provide an overview of the etiology of AD, the tools used in the diagnosis of AD, and the treatment of individuals with AD. In addition, the clinical presentation of the various stages of AD is described, and the psychosocial implications of this disease are discussed.