Reproductive period and dementia: A 44-year longitudinal population study of Swedish women.

ABSTRACT

INTRODUCTION: Longitudinal studies examining the effect of endogenous estrogens on dementia risk are needed to understand why women have higher dementia incidence than men after age 85. METHODS: A population-based sample of women with natural menopause (N = 1364) from Gothenburg, Sweden, was followed from 1968-2012. Information on endogenous estrogens (age at menarche and menopause, number of pregnancies, and months of breastfeeding) was obtained from interviews in 1968-1992. Dementia was diagnosed according to established criteria based on information from neuropsychiatric examinations and close informant interviews. RESULTS: We found that longer reproductive period was associated with increased risk of dementia (hazard ratio [HR] per year 1.06, 95% confidence interval [CI] 1.03-1.20) and Alzheimer's disease (AD) (1.06, 1.02-1.11), particularly for those with dementia (1.10, 1.04-1.17) and AD (1.15, 1.06-1.26) onset after age 85. DISCUSSION: These results may explain why women have higher dementia incidence compared to men after age 85, the age with the highest number of dementia cases.