If both parents have Alzheimer's, your risk soars

By Will Dunham

WASHINGTON (Reuters) - If both your parents have Alzheimer's disease, you probably are more much likely than other people to get it, researchers said on Monday.

Their study focused on 111 families in which both parents were diagnosed with Alzheimer's disease, the most common form of dementia among the elderly, and assessed the risk for developing it among the offspring.

The parents had 297 children who lived into adulthood. Of the 98 men and women who were at least 70 years old, 41 of them -- about 42 percent -- developed Alzheimer's disease, researchers at the University of Washington in Seattle found.

"That's greater than you would expect in the general population in that age group," Dr. Thomas Bird, one of the researchers, said in a telephone interview.

In the general population, risk for the disease begins to rise at about age 65, with the number of people developing the disease doubling every five years beyond that, experts say.

But about two-thirds of the adult offspring in the study still had not reached age 70. Counting all 297 of these adult offspring regardless of age, 23 percent already had been diagnosed with Alzheimer's disease, with the disease diagnosed on average at age 66, the researchers found.

Bird said that compares to the roughly one in 10 chance that the average person will develop the disease.

"I think it confirms that there's a strong genetic component in the disease and that's not a surprise," said Bird, whose study was published in the Archives of Neurology.