Prior Use of Hormone Therapy Associated with Reduced Risk of Alzheimer Disease

Compared with men, women are at increased risk of Alzheimer disease after ages 80 to 85 years, but long-term hormone replacement therapy (HRT) may reduce that risk among women, according to a new study completed by researchers at the Johns Hopkins Bloomberg School of Public Health. The study, published in the November 6, 2002, edition of theJournal of the American Medical Association (JAMA), found that women who underwent HRT were at a reduced risk of Alzheimer disease compared with women who did not. Women with more than 10 years of HRT treatment were at risk of developing Alzheimer disease comparable to that of men. The study also showed that a woman’s risk of developing Alzheimer disease decreased the longer that HRT was used, but there was no effect with current HRT use, unless duration exceeded 10 years.

The results of the study showed 88 women, or 4.7 percent of the female study participants, developed Alzheimer disease during the three-year study period. Women who used HRT had a 41 percent reduction in their risk of Alzheimer disease (26 cases among 1,066 women) compared with non-HRT users (58 cases among 800 women).

Peter P. Zandi, PhD, lead author of the study and assistant professor of mental hygiene at the Johns Hopkins Bloomberg School of Public Health, said, “These findings are important because they suggest when and how long women take HRT may determine its neuroprotective effects. If the findings are sustained, they could influence women's assessment of the risk-benefit ratio for initiating and continuing HRT, especially in light of other recent findings that indicate HRT may increase the risk of myocardial infarction, stroke, and breast cancer.”

The researchers stopped short of saying that HRT protects against Alzheimer disease. The authors wrote in their report, “We cannot exclude the possibility that HRT users differ from nonusers in other (important) attributes related to health in general and to Alzheimer disease in particular. The only way definitively to avoid this sort of difficulty is to conduct large-scale randomized prevention trials.”

“Hormone Replacement Therapy and Incidence of Alzheimer Disease in Older Women: The Cache County Study” was written by Peter Zandi, PhD, Michelle C. Carlson, PhD, Brenda L. Plassman, PhD, Kathleen A. Welsh-Bohmer, PhD, Lawrence S. Mayer, MD, David C. Steffens, MD, and John C. Breitner, MD. It is published in the November 6, 2002, issues of the Journal of the American Medical Association (JAMA).

The study was supported by a grant from the National Institutes of Health.