When it comes to protecting the brain, the timing of hormone replacement therapy (HRT) may be just as important as the treatment itself.
A new study suggests that starting HRT soon after menopause could lower a woman’s risk of developing Alzheimer’s disease, while delaying treatment until later in life may actually increase the risk.
The research, presented at the 150th Annual Meeting of the American Neurological Association, is the first large meta-analysis to focus on how the timing of HRT influences Alzheimer’s disease.
The analysis included data from more than 50 clinical trials and observational studies, covering tens of thousands of women.
Researchers looked not only at Alzheimer’s diagnoses and disease progression but also at brain changes seen in scans and laboratory tests.
Menopause marks the point when a woman’s natural estrogen levels fall sharply.
Estrogen is thought to help brain cells communicate, reduce inflammation, and protect against damage that can contribute to Alzheimer’s. HRT replaces some of that estrogen, usually through pills or skin patches, sometimes in combination with progestin or other hormone-related drugs.
The researchers found that women who began HRT within five years of menopause had a 32 percent lower risk of Alzheimer’s disease later in life.
Observational studies showed a 22 percent risk reduction for women who started HRT around the time of menopause compared with those who did not. But the benefits appeared to vanish if treatment was delayed.
In fact, starting HRT at age 65 or older was linked to a 38 percent increase in Alzheimer’s risk, particularly when progestin was included.
One possible explanation is that the brain may already have early signs of Alzheimer’s disease by the time a woman reaches her mid-60s. These include protein buildups and reduced blood flow, which make the brain more vulnerable to damage. Introducing estrogen at this stage may trigger inflammation or place extra stress on blood vessels, doing more harm than good.
“Starting hormone replacement therapy early may give the brain some protection, but if a woman already has Alzheimer’s or memory problems, hormone therapy won’t slow them down,” explained study author FNU Vaibhav, MBBS. He compared it to watering a plant: while it can help the plant grow, it won’t revive a plant that is already withering.
HRT is still primarily used to ease menopause symptoms such as hot flashes and poor sleep, and it can also benefit bone and heart health. Fewer than 5 percent of women in the U.S. currently use HRT, a sharp drop from nearly 26 percent in 1999.
The researchers caution that the evidence is not strong enough to recommend HRT solely for preventing Alzheimer’s. But for women considering the therapy for menopause symptoms, starting soon after menopause may offer some added protection for the brain.
What is clear, however, is that beginning HRT in one’s 60s or 70s is not advisable and may do more harm than good.
Source: KSR.
