The Effects of Estrogen on the Risk of Developing Dementia using the UK Biobank Data

Abstract

AbstractBackgroundThe incidence of dementia increases with postmenopausal women, which prompted the investigation of the role of estrogen in the development of dementia. We aimed to investigate the role of estrogen in the UK Biobank.MethodA total of 273,201 women were included in this study. Comprehensive interviews, medical history, body mass index (BMI), and the apolipoprotein E (APOE) genotype were obtained. Reproductive characteristics, including estrogen length and history of surgery, were used as exposure variables. The Cox Proportional Hazard model was used to estimate hazard ratios (HR) for the development of dementia, adjusting for age, education, the Townsend deprivation score, the APOE genotype, family history of dementia, BMI, smoking status, diabetes mellitus, hypertension, and hyperlipidemia.ResultThe mean estrogen length was 37.25 years (8.03 years). About 19% of women had a history of surgery. Compared to women with the lowest overall exposure to estrogen (Estrogen length ≤33), women with higher levels of cumulative estrogen had a decreased risk of dementia (34≤Estrogen length ≤37, HR = 0.79, 95% CI = 0.72‐0.89, p<0.001; 38≤Estrogen length ≤42, HR = 0.72, 95% CI = 0.65‐0.79, p<0.001; 43≤Estrogen length, HR = 0.77, 95% CI = 0.70‐0.85, p<0.001). Compared to women without a history of surgery, women with a history of surgery had an increased risk of dementia (HR = 1.08, 95%CI = 1.00‐1.17, p = 0.038).ConclusionThis study found that longer estrogen length had a decreased risk for dementia and a history of surgery had an increased risk for dementia. The results of this study suggested that estrogen might have a protective role in women’s development of dementia. The exact biological mechanism of the protective effects of estrogen in the brain needs to be elucidated in the future.