Adult women who undergo hormone replacement therapy at the beginning of menopause may decrease their risk of developing Alzheimer's disease by 30 percent, according to a new analysis.
Five years appears to be the magic number. Researchers from Johns Hopkins University found that women who started taking estrogen and progestin pills within that timeframe experienced the largest cognitive benefits.
Beginning replacement therapy later on may do more harm than good for a woman's mind. Evidence indicated that hormone treatment may actually increase a woman's risk for developing dementia, if she was older than 65.
Research into the mental effects of hormone replacement has traditionally offered conflicting results.
Results of previous studies have landed on both side of the fence—some imply that prescribed hormones may raise dementia risk, while others indicate that this form of treatment may offer cognitive benefits to aging women.
Peter Zandi, Ph.D., author of the current study, says his team's analysis is different because it suggests that there is an optimal window of opportunity for hormone therapy that women can capitalize on.
Prescribing hormone therapy for postmenopausal women has been a hotly debated topic in the medical community, as the treatment carries its share of risks.
Currently, the Federal Drug Administration (FDA) has only approved hormone pills, patches and intra-uterine devices (IUDs) to manage certain symptoms of menopause, such as hot flashes, vaginal dryness and infections and insomnia.
The National Institutes of Health (NIH) recommends postmenopausal women stick to small doses and short timeframes when using this form of treatment.
It was originally thought that supplemental hormones might provide women some protection against the chronic ailments more likely to befall them after menopause, including heart disease, osteoporosis and cancer.
But, the Women's Health Initiative (WHI)—a large-scale study begun by the National Institutes of Health to examine, among other things, the potential benefits of hormone replacement—initially failed to prove that this therapy offered older women any significant disease prevention perks.
The hormone replacement portions of the WHI investigation were halted prematurely, because it appeared as though artificial hormones carried some dangerous side-effects, including an increased risk of blood clots, stroke and certain cancers.
Since then researchers have continued to examine the results of WHI, seeking to identify additional trends between hormone therapy and women's health.
Zandi and his colleagues emphasize that their single study does not provide enough evidence to recommend hormone replacement as a way to ward off Alzheimer's disease in older women.
In a supplementary editorial on the study, Victor Henderson, M.D., M.S., of Stanford University writes, "While this well-designed study supports the possibility that short-term hormone use may reduce the risk of Alzheimer's disease, more research is needed before we can make new clinical recommendations for women."
The findings do help clear up the inconsistences seen in past research on hormone replacement and dementia risk, and lend support to the emerging theory that the duration and timing of therapy is an important factor for women and their doctors to consider.