Scientists have long known that estrogen, the primary female sex hormone, exerts protective effects on multiple organ systems. For example, estrogen helps maintain healthy blood lipid levels, reduces the risk of cardiovascular disease, and promotes bone health. Findings from a recent study suggest that estrogen protects against age-related cognitive decline and Alzheimer’s disease.
Alzheimer’s disease is a neurodegenerative disorder characterized by progressive cognitive decline and memory impairment. The disease disproportionally affects women, and scientists have identified distinct sex-related differences in Alzheimer’s disease symptoms, progression, biomarkers, and risk factors. Interestingly, the pathological hallmarks of Alzheimer’s disease begin to appear 10 to 20 years before the onset of symptoms – roughly coinciding with the period of menopause in women.
The study involved 99 women and 29 men (average ages, 52 years) who were cognitively normal. The women provided information about their reproductive histories, such as when they began menstruating, how many pregnancies they had, when they experienced menopause, and whether they had used hormonal contraceptives or hormone replacement therapy. Both women and men underwent memory testing and brain scans.
The scans revealed that the women who were peri- or postmenopausal had less gray matter volume in the temporal cortex, an area of the brain vulnerable to the effects of Alzheimer’s disease. Women who were premenopausal or had longer estrogen exposure due to their reproductive histories were more likely to have greater gray matter volumes. Exposure to estrogen did not influence performance on the memory tests directly, but participants with greater gray matter volume tended to perform better than those with lower volume.
These findings suggest that estrogen exposure exerts protective effects on brain health and illuminate the need for sex-specific research on Alzheimer’s disease pathology and therapies. This was a small study, however, and only identified associations between estrogen exposure and brain health, not causes.
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