Female reproductive factors and the risk of dementia: a nationwide cohort study

Background and purpose The aim was to investigate whether female reproductive factors are associated with dementia. Methods In all, 4 696 633 post‐menopausal women without dementia were identified using the Korean National Health Insurance System database. Data on reproductive factors were collected using a self‐administered questionnaire. Dementia was determined using dementia diagnosis codes and anti‐dementia drug prescription. Cox proportional hazards regression was conducted to assess the hazard ratio (HR) for dementia according to reproductive factors. Results During a median follow‐up of 5.74 years, there were 212 227 new cases of all‐cause dementia (4.5%), 162 901 cases of Alzheimer’s disease (3.5%) and 24 029 cases of vascular dementia (0.5%). The HR of dementia was 1.15 [95% confidence interval (CI) 1.03–1.16] for menarcheal age ≥17 years compared with menarcheal age 13–14 years, 0.79 (0.77–0.81) for menopausal age ≥55 years compared with menopausal age