Age is the most important known risk factor for AD. The disease usually begins after age 60, and risk goes up with age. The number of people with the disease doubles every 5 years beyond age 65. About 5 percent of men and women ages 65 to 74 have AD, and nearly half of those age 85 and older may have the disease. It is important to note, however, that AD is not a normal part of aging. Family history is another risk factor. Other risk factors include hypertension, diabetes and high cholesterol, as well as life style factors such as a lack of exercise, social isolation, depression, certain nutritional deficits, repeated head trauma and stress.
