Having a shorter reproductive span is associated with an increased risk for dementia in women, according to a study published online March 28 in Neurology.
Paola Gilsanz, Sc.D., from the Kaiser Permanente Division of Research in Oakland, California, and colleagues examined the correlation between indicators of estrogen exposure from women’s reproductive periods and dementia risk in a population of 15,754 female participants. Women reported age at menarche and menopause and hysterectomy status in midlife (mean age, 51.1 years). Dementia diagnoses were abstracted from medical records (mean age at start of dementia follow-up, 76.5 years).
Dementia developed in 42 percent of women. The researchers found that menarche age at ≥16 versus age 13.0 years correlated with an increased dementia risk (adjusted hazard ratio, 1.23) after adjusting for demographics and life course health indicators. The risk for dementia was increased in association with natural menopause age <47.4 years (mean menopause age; hazard ratio, 1.19). The risk for dementia was increased 20 percent with reproductive spans <34.4 years (hazard ratio, 1.20). Hysterectomy also correlated with an increased dementia risk (hazard ratio, 1.08).
“Our results show that less exposure to estrogen over the course of a lifetime is linked to an increased risk of dementia,” Gilsanz said in a statement. “We did not have enough data to account for other factors that could affect estrogen levels, like pregnancies, hormone replacement therapy or birth control, so more research is needed.”