Women are twice as likely to develop Alzheimer’s disease – could this be why?
The study, which was conducted by researchers from the Washington University School of Medicine in St. Louis and published in the journal braincompared the brain activity of male and female rodents when they were exposed to a large amount of stress.
The researchers measured the level of amyloid beta-Alzheimer’s key protein1— in the brains of male and female mice every hour for 22 hours, starting eight hours before the mice were stressed. First, they measured blood levels of stress hormones and noticed that both sexes experienced the same amount of stress. However, they found that their brains’ response to stress differed significantly between the sexes, with the brains of male mice reacting to a stressful situation quite differently than the brains of female mice.
Although male and female mice found the experience equally stressful, the female mice had significantly higher levels of beta-amyloid during the first two hours after experiencing the stressful situation. In addition, its levels remained elevated throughout the monitoring period. However, in males, the researchers mostly saw no changes in beta-amyloid levels (except for 20% of male mice, which showed a very weak, delayed increase in beta-amyloid levels).
Essentially, this research has identified key ways in which the brains of men and women perceive stress very differently, and further research indicates that this difference is driven by a cellular stress response pathway within brain cells. Female rodents have neurons that perceive the stress hormone, which is associated with increased levels of beta-amyloid, but male rodents do not have these neurons and therefore do not perceive the stress hormone.
While it’s unclear whether this fundamental difference exists in humans—or is just as marked—the research points to biological differences between men and women when it comes to stress.
“There is a fundamental biological difference between males and females in how they respond to stress at the cellular level in both mice and humans,” said John Cirrito, Ph.D., study author and associate professor of neurology. statement. “We do not believe that stress is the only factor influencing the gender difference in Alzheimer’s disease. There are many other differences between men and women—in hormones, lifestyle, [and] other diseases they have that no doubt contribute in some way. But this stress is a driver of one aspect of this gender difference, I think very likely.”
While it is is not the first study to link stress to Alzheimer’s disease2, it is unique in that it tries to find out why women are much more often diagnosed with this disease than men. Biological differences in response to stress should not be discounted as a major factor.