There’s new evidence that a woman’s levels of female sex hormones, including estrogen and progesterone, can influence her risk of Alzheimer’s and other forms of dementia.
Women are less likely to develop dementia later in life if they begin to menstruate earlier, go through menopause later, and have more than one child, researchers reported Monday at the Alzheimer’s Association International Conference in Chicago.
And recent studies offer hints that hormone replacement therapy, which fell out of favor more than a decade ago, might offer a way to protect a woman’s brain if it is given at the right time, the researchers said.
The findings could help explain why women make up nearly two-thirds of people in the U.S. with Alzheimer’s, says Maria Carrillo, the association’s chief scientific officer.
“It isn’t just that women are living longer,” Carrillo says. “There is some biological underpinning. And because of the large numbers of women that are affected, it is important to find out [what it is].”
Scientists have long suspected that sex hormones such as estrogen and progesterone play a role in Alzheimer’s. And two studies on dementia and what occurs during a women’s reproductive years support that idea.
One of the studies looked at nearly 15,000 women in California. And it found an association between a woman’s reproductive history and her risk of memory problems later in life.
The risk of dementia for women who had three or more children was 12 percent lower than the risk for women who had one child, according to Paola Gilsanz of Kaiser Permanente Northern California Division of Research, and Rachel Whitmer of the University of California, Davis.
Also, women who began to menstruate earlier and went through menopause later were less likely to develop dementia. Menopause at age 45 or younger seemed to increase the risk by 28 percent.
Another study of 133 elderly women in the U.K. found that the more months of pregnancy they experienced during their lives, the lower their risk of developing Alzheimer’s.
The findings all suggest that female sex hormones — which rise at puberty and during pregnancy, then fall at menopause — are somehow affecting a woman’s risk of developing Alzheimer’s and other forms of dementia. The results also suggest that greater exposure to these hormones, through more pregnancies or more reproductive years, can reduce a woman’s risk.
But it’s still not clear whether the mere presence of female sex hormones is a reason that the frequency of Alzheimer’s is greater in women than in men. To read more from Jon Hamilton, click here.