FEMALE REPRODUCTIVE FACTORS AND DEMENTIA

Article of the month of July submitted by Dr David Burke

Evidence suggests that estrogen may have a positive impact on memory, affect, and motor coordination in women. This study was designed to investigate the association between female reproductive factors and the incidence of dementia.
The National Health Insurance Service (NHIS) is the single insurer in Korea, providing medical care to 97% of the Korean population. From the NHIS data 4,775,398 post-menopausal women were identified. Age at menarche and age at menopause were determined, with the duration of fertility calculated as the interval between the two. The number of children and total lifetime history of breast feeding was recorded for each woman. The duration of hormone replacement therapy was categorizes never, less than two years, two-five years or five or more years. The endpoint of the study was newly diagnosed dementia including Alzheimer’s disease, vascular dementia or other dementia.

During a median follow-up of 5.74 years, there were 212,227 cases of all-cause dementia. In a dose-dependent manner, the incidence of all-cause dementia increased significantly with later age of menarche, earlier age of menopause, shorter duration of fertility and never user of HRT (p< 0.001). This association was noted for both Alzheimer’s disease and vascular dementia. Compared to women who experienced menopause before the age of 40 years, those will underwent menopause after the age of 55 years had a significantly lower risk of dementia (HR 0.79). Compared with those who never used HRT, those who had used HRT had a 15% lower risk of dementia. Those who used oral contraceptives had 10% lower risk of dementia compared to nonusers.

Conclusion: This retrospective study of women in South Korea found that later menarche, earlier menopause and shorter duration of fertility were each independently associated with an increased risk of dementia postmenopausal women.

Yoo, J et al. Female Reproductive Factors and the Risk of Dementia: A Nationwide Cohort Study. Eur J Neurol. 2020, Aug; 27(8): 1448–1458.