Sex hormones, SHBG and cognitive performance among older Australian women: an observational study.

OBJECTIVE:This study aims to explore the associations between sex hormones and cognitive performance in older women. METHODS:Associations between sex hormones, sex hormone binding globulin (SHBG) and cognitive performance were examined in women aged at least 70 years, without dementia and not using medications that influence sex hormones. Linear and generalized linear regression models included age, body mass index, education, smoking, alcohol, living circumstances, diabetes, hypertension, depression and impaired renal function. RESULTS:The included 5511 women had a median (interquartile range) age of 73.9 (71.6-77.6) years. No associations were found for estrone, estradiol, testosterone or dehydroepiandrosterone and cognitive performance. SHBG concentrations above quartile 1 (Q1) were significantly inversely associated with processing speed (Q2, β = -0.94, 95% confidence interval [CI] - 1.64 to -0.24, p = 0.009; Q3, β = -0.82, 95% CI -1.53 to -0.10, p = 0.025; and Q4, β = -0.95, 95% CI -1.70 to -0.20, p = 0.013). CONCLUSIONS:Sex hormones were not associated with cognitive performance. The finding that low SHBG is associated with better processing speed warrants further investigation. The null findings for the sex hormones establish a firm baseline to confidently explore the association between sex hormones and longitudinal cognitive performance in this population. TRIAL REGISTRATION:International Standard Randomized Controlled Trial Number Register (ISRCTN83772183) and ClinicalTrials.gov (NCT01038583).