Women Live Longer and Get More Dementia in Old Age

Women may have the edge over men in longevity, but men who make it into their nineties are less likely than women to have dementia. Researchers at the University of California Irvine made this surprising discovery in one of the first ever studies of dementia in people 90 and over, called the “oldest old,” who now constitute the fastest growing segment of the US population.

DEMENTIA IN THE OLDEST OLD

Starting around age 65, the odds of having dementia climb steadily upward for everyone. Dementia afflicts about 1% of 60- to 64-year-olds… 5% to 8% of 65- to 74-year-olds… and up to 20% of those 75 to 84. Generally speaking, prevalence is higher in women — and this new research shows this becomes more so with advancing years.

In their analysis of 911 individuals age 90 and older in southern California (10% were 100 or older), epidemiologist Maria M. Corrada, ScD, and her colleagues found that…

  • Nearly half the women (45%) experienced some form of dementia, compared with only 28% of the men.
  • The likelihood of having dementia doubled every five years in women after reaching 90, but not in men.
  • Women with a higher education were 36% to 45% less likely to have dementia than women with a high school education or less.

These results were published in the July 2, 2008, online issue of Neurology, the medical journal of the American Academy of Neurology.

GENDER AND EDUCATION AFFECT PREVALENCE

According to Dr. Corrada, there are two possible reasons for the striking gender differences — women are either at a higher risk for dementia or they live longer with the disease. Although the underlying reasons remain unclear, Dr. Corrada told me that the data she reviewed in this study lead her to believe it is the second — that, just as healthy women live longer than healthy men, women with dementia live longer than men with dementia.

OTHER DEMENTIA FACTORS

Dr. Corrada and her team also learned that the finding that women with higher education were less likely to have dementia did not hold true with men. Though researchers aren’t sure why this is so, it may be that educated women live longer, which in turn affects dementia prevalence. Another theory is that women with a higher education are different from men with a higher education, particularly true of this older generation of women who are less likely to have been able to receive advanced degrees.

This study is about the likelihood of having dementia, not risk for the condition, notes Dr. Corrada. For this reason, it does not address prevention. That said, she adds that the best way we know at present to help reduce risk of dementia is simply to lead a healthy life: Eat nutritious foods and a balanced diet, exercise, keep your brain active and engaged, and spend lots of your time with friends and loved ones.