Menopause is a milestone of aging, marking the end of a woman’s reproductive years. But researchers have always wondered whether menopause can hasten aging by triggering age-related changes or whether it’s simply a consequence of a body that’s reached a certain biological age.
In two new studies, one published in PNAS and the other in Biological Psychiatry, researchers have found strong evidence that menopause may actually accelerate aging in women.
Steve Horvath, professor of human genetics and biostatistics at University of California Los Angeles, and his team measured the changes in a group of women’s DNA and concluded that the cells of women who had experienced menopause speed up aging processes by about 6%.
Horvath and his team studied 3,100 women enrolled in the Women’s Health Initiative, a large ongoing study of women’s biology, who provided samples of DNA from their blood, saliva and cheek tissue. They analyzed changes in the DNA called epigenetic alterations that serve as a marker for a cell’s age; these changes serve as a type of aging clock for the cells. “The epigenetic clock is similar to counting rings on a tree to assess its age,” says Horvath.
He focused on the epigenetic changes because earlier work hinted that women who have their ovaries removed—and therefore experience early menopause—tend to show signs of aging sooner than women who don’t need the surgery. Other work also showed that some of these women who then took hormone therapy to replace the hormones that stopped after their surgical menopause showed signs of having younger or restored cells compared to women who didn’t take the hormones.
Taken with his current epigenetic results, says Horvath, “All of these arguments very, very strongly suggest that the loss of hormones that accompany menopause accelerates or increases biologic age.”
In the other study, another group of researchers from UCLA found that poor sleep, particularly insomnia, can also trigger similar acceleration in aging. Those aging-related changes can make chronic diseases such as heart disease and cancer more likely.
The two studies highlight the increasing focus on biological age, as opposed to chronological age: in other words, how old people really are, as indicated by their cells and tissues. Depending on people’s genes and lifestyle habits, they can age at different rates, and Horvath says the epigenetic evaluation is a much better indicator of aging than a birth date.
“We really couldn’t measure biological aging in the past,” says Horvath. “We didn’t have a molecular measure of age, of how old cells and tissues really were. Now we have a wonderful opportunity to really study what stress factors affect biological age, and what could be done to slow aging.”
Part of that solution may include re-visiting the role that hormone therapies might play, particularly for women, in slowing the aging clock. Horvath is not advocating that post-menopausal women start taking hormone replacement therapy as a way to stay young, but it’s possible that in the future, newer versions of these hormones, with fewer side effects, could be a part of aging gracefully. “In the future there may be low-level hormone therapies that are almost like a statin pill,” he says of the popular cholesterol-lowering medications that can reduce the risk of heart disease. “But I don’t think we have that yet.”