Abstract
Abstract Background Age-standardised prevalence and deaths for dementia have been reported to be higher in women compared with men. The role of female-specific endocrine and reproductive events in modulating dementia risk needs to be further clarified to explain some of these sex disparities. Method The UK Biobank recruited over 500,000 middle-aged women and men. After 11.3 years, 3,701 (45% women) incident dementia occurred. Cox proportional hazard regressions estimated hazard ratios (HRs) for reproductive factors and hormone use with dementia in women; number of children in both sexes. Result Adjusted HRs (95% CI) for dementia were 1.20 (1.08, 1.35) for menarche at <12, 1.24 (1.10, 1.39) at ≥15, compared to 13 years; 1.29 (1.12, 1.49) for menopause at <47 compared to 50 years; 1.13 (1.01, 1.27) for hysterectomy; 0.80 (0.72, 0.90) for use of oral contraceptive pills, and 1.56 (1.40, 1.73) for hormone replacement therapy. The number of children and dementia risk were similarly associated for women and men. Conclusion Hormonal transition and reproductive experiences were associated with women's dementia risk, although the biological factors associated with childbearing are unlikely to account for the risk variation in women. </p>