July 14, 2008
Women over age 90 are significantly more likely to have dementia compared to men in their 90s, according to a new analysis of the oldest old. The study looked at all forms of dementia, of which Alzheimer's is the most common form. The findings were published in the online edition of Neurology, the medical journal of the American Academy of Neurology.
More women than men live to age 90 and beyond. Research shows that dementia risk for both men and women increases from age 65 to 85, but this most recent study is one of few that looked at people over age 90.
"While men don't typically live as long as women, those who do make it to age 90 appear to be much less likely to have dementia and also have a shorter survival time when they do have dementia," according to study author Maria Corrada, Sc.D., with the University of California, Irvine.
Researchers reviewed an analysis of more than 900 people age 90 and older who were living in a retirement community in Orange County, Calif. Of those, 375 had Alzheimer's disease or other forms of dementia. The population studied tended to be white and of high socioeconomic status, and about two thirds were women.
The study found that women were nearly twice as likely to have Alzheimer's and other forms of dementia in their 90s compared to men of the same age. The prevalence of dementia overall in very elderly women was about 45 percent, compared to 28 percent for men.
"As more and more people reach age 90, our findings provide further evidence that more needs to be done to provide adequate resources to care for the increasing number of very old people with memory problems," Dr. Corrada said.
In addition, the study found that women with a higher education appeared to be as much as 45 percent less likely to have dementia compared to women with less education.
The 90 plus age group, or the "oldest-old," is the fastest growing segment of the elderly population, according to the U.S. Census.
The study was supported by the National Institutes of Health and the Al and Trish Nichols Chair in Clinical Neuroscience.
M. M. Corrada, Sc.D., R. Brookmeyer, Ph.D., D. Berlau, Ph.D., et al: "Prevalence of Dementia After Age 90: Results from the 90+ Study." Neurology, Volume 71, July 2, 2008, pages 337-343.