Can hormone therapy (HT) protect you from dementia? After all, estrogen protects neurons in animal studies. Plus, more women than men get Alzheimer’s—and some scientists have speculated that naturally falling estrogen levels during and after menopause might increase the risk. If so, replacing that estrogen with HT might be protective against Alzheimer’s.
The latest research sheds new light on the issue. The key, it turns out, isn’t whether a woman takes HT—but when and for how long.
Background: Results from previous studies have been inconsistent. Some have shown that HT was statistically linked to a reduced risk for Alzheimer’s, while other studies have shown increased risk. So researchers from the University of Eastern Finland decided to delve into a robust database to try to get an answer.
New study: All women age 47 to 56 living in Kuopio Province in Finland—more than 13,000—were mailed questionnaires about hormone therapy use every five years for 20 years, from 1989 until 2009. The women were also part of a national medical registry, so researchers could reliably track which ones were diagnosed with Alzheimer’s disease over that time.
Results: For most women, HT didn’t have an effect on Alzheimer’s risk. But for one group of women, the results were striking…
- Women who started HT right around the time they stopped menstruating in their early 50s—and who continued HT for more than 10 years—had a decreased risk of developing Alzheimer’s. One possible explanation is that there is an “estrogen window” in which hormone therapy may be protective—something already shown for cardiovascular risk.
Bottom line: Studies such as this can find statistically relevant associations but can’t prove cause and effect. Only carefully controlled clinical studies can determine whether hormone therapy should be prescribed for the purpose of preventing dementia.
So it’s too early to use Alzheimer’s risk as a factor in determining whether HT is right for you. But this study does reinforce other evidence that when it comes to hormone therapy, timing is important. For instance, other research cited by the study authors has found an increased risk for Alzheimer’s among women who start hormone therapy at an older age (age 64, on average). If you do decide to take HT—for relief of bothersome menopausal symptoms such as hot flashes, for instance—the new research is more evidence that starting earlier may be safer and possibly more beneficial than waiting a decade or more after menopause hits.