MONDAY, May 6 (HealthDay News) -- Families with exceptional longevity also appear to have later onset of dementia, a new study suggests.
Ultimately, the same percentage of people in families surviving to 90 and beyond are prey to Alzheimer's disease as others, but the progressive brain disorder tends to develop later in life, the researchers say.
"The goal of the study was to determine whether or not members of exceptionally long-lived families are protected against cognitive [mental] impairment consistent with Alzheimer's disease," said lead researcher Stephanie Cosentino, an assistant professor of neuropsychology at Columbia University Medical Center in New York City.
The answer: Yes, except for the oldest of the old.
Although the reason for the delayed onset of dementia in the very old isn't clear, Cosentino said "there may be specific genetic pathways related to preserved cognition in these families." Alzheimer's disease is the most common cause of dementia among the elderly.
Cosentino's team followed more than 1,800 participants (1,510 family members and 360 spouses as "controls") in the U.S.-Danish Long Life Family Study, which is evaluating genetic and non-genetic factors associated with extreme longevity.
For the current report, published online May 6 in JAMA Neurology, they looked at the onset of Alzheimer's disease among blood relatives within long-living families and compared that with similar data on their spouses.
Older family members, average age 88, had similar rates of mental decline as their spouses, Cosentino found. However, sons and daughters, average age 70, of exceptionally long-lived people had less than half the risk of Alzheimer's disease than their similarly aged spouses, she said.
"Overall, a higher proportion of family members than their spouses were dementia-free until age 90," Cosentino said. "After 95 y
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