Women and Alzheimer’s Disease
The Alzheimer’s Association released a report on March 19, 2014 announcing that women at age 65 have a lifetime risk of developing Alzheimer’s that is almost twice the lifetime risk of men at age 65. This information begs the question why women are more prone to this disease.
There are other explanations for the imbalanced gender toll of Alzheimer’s Disease: women live longer than men. Alzheimer’s Disease is, in most cases, a disease of old age, and women live longer than men. Based on 2010 census data, women comprise 57% of the US population over the age of 65, but they comprise 67% of the population over the age of 85. Therefore, by measuring the lifetime risk of developing the disease starting at age 65, the results will reflect longevity as well as vulnerability to the disease. However, longevity alone does not explain the higher prevalence of Alzheimer’s Disease among women.
Researchers have examined the potential role of estrogen as a protective agent for almost two decades with inconsistent, controversial, and differing results. Some studies have found that estrogen taken during menopause protects against Alzheimer’s Disease, while others have found no protective effect. In looking at these study designs, differences appear that might account for the range of results. Different studies used different hormones, focused on women of different ages, or with different histories of estrogen use. One theory that has gained support is the Timing Hypothesis, which is that women need to start estrogen replacement before menopause to gain its protective advantages against cognitive decline. Proving this hypothesis has been difficult as many women have refused to take estrogen after a very large Women’s Health Study was stopped in 2002 when its data showed that women on the estrogen had higher rates of heart attacks and breast cancer. Since 2002, clinicians have refined the guidelines for the use of hormones in menopausal women, limiting its use to symptomatic menopausal women for short periods of time. The history of estrogen studies in a form understandable to those of us who are not clinicians is here. However, short term use of estrogen for women in their 50s will not yield any further understanding of its protective attributes against Alzheimer’s for many more years.
Now that the Alzheimer’s Association is putting a spot light on the disparate impact the disease has on women, it would be helpful if the Association would help develop a coordinated research effort to understand the interplay between hormones and cognitive function, including the types of hormones that are protective and the time and duration of treatment in order to experience protective results.