Two Parents With Alzheimer's Raises Child's Risk

By Steven Reinberg
HealthDay Reporter
Monday, March 10, 2008; 5:00 PM

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MONDAY, March 10 (HealthDay News) -- If both parents have Alzheimer's disease, their children face an increased risk of developing the condition, a new study suggests.

Overall, 42 percent of offspring whose parents both had Alzheimer's went on to develop the disease themselves by age 70, the researchers found.

The risk is also greater of developing the disease early if additional relatives had Alzheimer's disease, researchers say.

Most experts agree that genetics plays a role in Alzheimer's disease, but the degree to which genetics is responsible for the disease is still unclear.

"There probably is an increased risk of Alzheimer's disease in the children of spouses that both have the disease," said lead researcher Dr. Thomas D. Bird, a professor of neurology at the University of Washington School of Medicine in Seattle. "The exact magnitude of the risk, we don't know yet."

Bird's group is trying to determine the genetic factors at play in Alzheimer's disease. So far, only one genetic factor has been documented, Bird said. "The hope is, there will be others and they will be found," he said. "Presumably, these children would have a higher concentration of those factors. So, that's what ought to be looked for."

The report appears in the March issue of the Archives of Neurology.

In the study, Bird's team collected data on the grown children in 111 families where both parents had Alzheimer's disease.

"There were 98 children who had gotten to age 70, and of that group 41 had developed Alzheimer's disease. That's about 42 percent," Bird said. "We felt that's pretty important."

The researchers found that for the total group of 297 children, 22.6 percent had developed Alzheimer's disease. That compares with an expected 6 percent to 13 percent of people in the general population who would be expected to develop the disease.

Alzheimer's typically started at about age 66 in children with two affected parents, the study found, and the odds of developing Alzheimer's rose as the children got older. In fact, 31 percent of those older than 60 developed Alzheimer's, as did 41.8 percent of those older than 70.