WEDNESDAY, July 2, 2008 (HealthDay News) -- Not as many men as women make it to their 90s or beyond, but those who do have an advantage over their female counterparts: Researchers found that males aged 90 and older are more likely to avoid dementia than women of similar age.
There's no clear reason for the striking discrepancy, according to the study, which found signs of senility in a full 45 percent of women aged 90 and older from a southern California retirement community. Men weren't immune to mental decline, however, since 28 percent of them also suffered from dementia.
Still, "given the increasing number of people (aged 90 and older) this can become a fairly big public health problem," said study lead author Maria Corrada, an assistant adjunct professor of neurology at the University of California, Irvine. "We need to be prepared for that. Dementia requires a lot of care, and a lot of money needs to be spent on caring for these people."
Dementia -- also known as senility -- refers to the mental confusion that can strike the elderly. Alzheimer's disease, stroke and brain injuries can lead to the condition, although the cause is sometimes unknown.
Researchers know little about how senility affects the so-called "oldest old" -- people 90 and older. There are now an estimated two million American in this age group and that number is projected to grow substantially as the population ages.
In the new study, the researchers examined a survey of 911 men and women over the age of 90 between 2003 and 2006. In the 1980s, all the participants had lived in the Leisure Village retirement community in Orange County, Calif., and took part in another study at that time.
Two-thirds of the participants were women and most were white, upper-middle class and well-educated. In some cases, the researchers interviewed them by phone or in person; in others, researchers talked to someone else, such as a relative or caregiver.
The study findings were published online July 2 in the journal Neurology.
Why the discrepancy between the genders in terms of dementia risk? Although the study didn't look at when the participants started showing signs of senility, it's possible that women may simply live longer with the condition than men, Corrada said. Women, after all, live longer than men in general.
It's also possible that men who manage to reach the age of 90 have "the best protoplasm," said William Thies, vice president for medical and scientific affairs with the Alzheimer's Association. In other words, men have to be in pretty good shape to make it that far.
Corrada and her colleagues also found that women with higher levels of education were less likely to show signs of senility. More education didn't seem to have any effect in men, however.
"Education may mean something different for men and women in this age group," Corrada said.
Other research has linked education to brain health, Corrada added. "People who have more education and more intellectual attainment in their lives are less likely to become demented," she said. "That may be simply because they start out so much better than everyone else (brain-wise) that they can cope better" with aging.
Learn more about dementia from the American Academy of Family Physicians.