Hormone Treatment May Reduce Risk of Alzheimer's Disease
When it comes to hormone treatment, science seems to have more than one answer.
-- by Nina Lincoff
Hormone therapy is a hot topic in the medical research community, and it has nothing to do with hot flashes. Even though the U.S. Preventive Services Task Force (USPSTF) recommended earlier this week against using estrogen or progestin for treatment of chronic medical diseases in postmenopausal women, it seems that the door is not quite ready to be shut on hormone therapy. Findings from a Cache County Study published by the American Academy of Neurology reported that hormone therapy (HT) may be beneficial in reducing risk of Alzheimer’s disease if taken during a critical time window near menopause.
Nearly 1,800 women ages 65 or older reported use of HT near menopause between 1995 and 2006 for this study. Incidence of Alzheimer's disease dementia was closely evaluated. The results run slightly counter to what the USPSTF is reporting, although with any scientific study or recommendation, there is always room for further research. For women who used any type of HT within five years of menopause—an earlier window in terms of the USPSTF survey—there was a 30 percent lower risk of AD, particularly if HT was continued to ten or more years.
Because of the conflicting studies and reports circulating on the subject of HT efficacy, a deeper look at other factors affecting and associated with HT is needed.
The Expert Take
"HT has been an ongoing discussion in the field,” said study author Dr. Peter Zandi, Ph.D. “Many different observational studies have shown that hormone therapy has been beneficial for women in the older bracket for AD.” Zandi notes that a previous large study by the Women’s Health Initiative provided a randomized look at HT association with prevention and found that HT could potentially be harmful to postmenopausal women. Those results stymied further research in HT, said Zandi, but this study of nearly 1,800 women suggest that HT requires deeper investigation.
“There may be a big discussion as to why the results were so divergent, and several theories have been suggested that there was an issue with timing,” said Zandi.
The study of the Cache County population found positive effects when HT was started closer to menopause and continued for over a decade. These women were often using HT for treatment of postmenopausal symptoms. The USPSTF recommendation only applies to postmenopausal women considering HT for clinical medical conditions. However, the divergent findings of these studies beg for further study of HT and how a different timeline for treatment may help lower incidence of AD.
The next ideal step would be to conduct a randomized trial with women who are entering menopause. That however, is both ethically and logistically difficult, said Zandi, because the positives and negatives of HT is still up in the air.
Source and Method
The researchers followed 1,768 women ages 65 and older for 11 years. Participants would provide history of their HT use, as well as when menopause began for them. Out of this group, 1,105 had used HT, which involved the use of either estrogen alone or with a progestin. Alzheimer's disease dementia was developed by 176 of the women in the study—87 of these women had taken hormone therapy, and 89 had not.
Women who used HT within five years of menopause in this study had a 30 percent lower risk of developing Alzheimer's dementia. Risk did not rise or fall among women who started HT five or more years after menopause. Conversely, women who used HT involving combined estrogen and progestin when they were at least 65 were found to have a higher risk of dementia.
As is often the case in medical research, there needs to be further study on the matter. Literature on HT is plentiful, and but the results just don’t seem to line up.
The Cache County study was just one that looked at the association between HT and lowering risk of AD. Since 2006, types of HT used by participants was carefully considered alongside follow-up. What was found was exciting: in meta-analysis, researchers reported a 24-44 percent possible reduction in AD risk through proper use of HT. The difference seems to be in a ‘critical window,’ said Zandi. Women who started HT within five years post-menopause and continued for ten years or more had a much lower risk of AD than those who waited or only used AD for a couple years.
“The findings are interesting, and of course they suggest that more studies are needed,” said Zandi. “Nature doesn’t always reveal itself and provide concrete answers.”
Zandi recommends against women changing their behavior towards HT just yet. "They should consult their physicians," he said. "Women should not just take HT because of one positive conclusion."
The Women’s Health Initiative is mentioned by both Zandi and the USPSTF and was published in the Journal of the American Medical Association in 2002.