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Dear Dr. Roach: My wife and her two siblings all have Alzheimer's disease. My wife is 81 and now lives in a nursing home. Her sister is 86 and in hospice, and their brother died at age 80. What is the risk of getting Alzheimer's if a family member has it? -- Anon.
Dr. Roach: Alzheimer's disease is a common cause of dementia, the impairment of memory and other cognitive brain function, such as decision-making ability. The biggest risk factor for Alzheimer's disease is age, with the rate of Alzheimer's roughly doubling every five years after age 65. Having a first-degree relative (a parent or sibling) who has it increases the risk of developing Alzheimer's disease at any age; the absolute increase in risk can be as much as 30 percent higher. The risk appears to be even higher for blacks. However, the older the relative at the time of diagnosis, the less the increased risk for the family member. So, having a family history definitely increases the risk but doesn't guarantee diagnosis.
Although there are genetic tests currently available, I don't recommend them at this time. They don't accurately predict who will and won't develop Alzheimer's disease: They only can point to an increased or decreased risk.
The Alzheimer's Association, at www.alz.org, has an outstanding website with many resources.