Reproductive Factors and the Risk of Incident Dementia: Results From the UK Biobank

Abstract

Background: To examine the risk of incident all-cause dementia associated with reproductive factors in women, and the number of children in both sexes; and whether the effects vary by age, socioeconomic status (SES), smoking status and body mass index in the UK Biobank.Methods: A total of 273,265 women and 228,966 men without prevalent dementia from the UK Biobank were included in the analyses. Cox proportional hazard regressions estimated hazard ratios (HRs) for reproductive factors with incident all-cause dementia.Results: Over a median of 11.3 years follow-up, 1,680 dementia were recorded in women and 2,021 in men. Adjusted HRs (95% confidence intervals (CIs)) for dementia were 1.20 (1.08, 1.35) for menarche <12 years, and 1.24 (1.10, 1.39) for menarche ≥15 years compared to 13 years; 0.86 (0.74, 1.00) for ever been pregnant; 0.80 (0.69, 0.93) for each abortion; 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 oral contraceptive pills use; and 1.56 (1.40, 1.73) for hormone replacement therapy (HRT) use. The U-shaped associations between the number of children and the risk of dementia were similar for both sexes. There was evidence for early (natural and artificial) menopause, and a greater number of children were associated with a higher risk of dementia among women of relatively lower SES only.Conclusions: Shorter cumulative endogenous estrogen exposure in women is associated with higher dementia risk, although female biological factors involved in childbearing are unlikely to account for risk variation.

Sex-Specific Associations of Diabetes With Brain Structure and Function in a Geriatric Population

“…These important cardiovascular parameters are therefore often not registered in medical files, as is the case in our dataset (Wilkins-Haug et al, 2015 ). It has long been known that menopausal status and the timing of menopause influence cardiovascular risk, abdominal obesity, occurrence of DM, and clinical course of dementia (Archer, 2009 ; Gong et al, 2021 ; Hickey and Mishra, 2021 ). They may therefore also have affected the clinical outcome in our study.…”