Two thirds of those with Alzheimer’s disease are women, and researchers are finding new clues about why.
One logical reason is that women tend to live longer than men, and Alzheimer’s disease is more common with advancing age. So if there are more women than men living into their 70s, 80s and 90s, more of those affected with Alzheimer’s would be women. About one in six women over 70 have Alzheimer’s disease.
But biological and social factors likely also play a role, according to new research. Understanding these differences could lead to more effective treatments for Alzheimer’s.
In one study, researchers at Vanderbilt University Medical Center found that women and men with Alzheimer’s disease differed in the way that their brains processed tau, a distorted protein that builds up in brain cells and kills them. Tau affects the memory centers of the brain at first and spreads through the brain almost like an infection, killing more and more cells as Alzheimer’s advances.
The researchers used brain scans to compare the brains of more than 400 men and women. Some had mild cognitive impairment, a state that can last several years and that is accompanied of various mild symptoms such as short-term memory loss but does not qualify as a specific type of disease. Mild cognitive impairment often progresses to full-blown Alzheimer’s disease.
In women with mild cognitive impairment, tau was spread through more widespread areas of the brain than men with the condition. The findings suggest that in women, tau spreads more easily and propagate more quickly through the brain.
In another study of more than 6,000 women who were born between 1935 and 1956, researchers found that women who had had paid jobs were less likely to get a diagnosis of Alzheimer’s disease after age 60 than their peers who hadn’t worked. Those who had worked generally had more robust memories and less memory decline than those who hadn’t worked.
Dr. Elizabeth R. Mayeda, assistant professor of epidemiology at UCLA’s Fielding School of Public Health and the study leader, noted that there were no discernable difference in brain health before age 60. But between the ages of 60 and 70, average memory performance for non-working women declined twice as fast as women who were working.
Work provides mental stimulation and social interaction, two factors that have been tied to a lower risk for Alzheimer’s disease, other research has shown.
The findings of both studies were presented at the Alzheimer’s Association International Conference in July in Los Angeles.
Other research has shown that estrogen and other hormones may account for differences in the brains of men and women. Genetic factors may also account for differences in susceptibility to Alzheimer’s disease as well.
“Understanding how different biological processes influence our memory is a really important topic,” said Sepi Shokouhi, assistant professor of psychiatry and behavioral sciences at Vanderbilt and the lead investigator of the study on tau. “Sex-specific differences in the brain’s organization may map into differences at a neurobehavioral and cognitive level, thus explaining differences in the prevalence of neurodegenerative disorders and helping us develop appropriate treatments.”
Source: Vanderbilt University. University of California, Los Angeles. Alzheimer’s Association International Conference, Los Angeles, July 2019.