Alzheimer's disease is a condition marked by the deterioration of mental function. The disease usually begins in late middle life and results in death in 5 to 10 years. Patients with Alzheimer's disease typically suffer from memory loss, confusion, and disorientation. The condition has become a major medical and social problem in the United States because of the increasing number of people living beyond the age of 65. The actual cause of Alzheimer's disease is unknown.