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DIFFERENTIAL INFLUENCE OF SEX HORMONES, GONADOTROPINS, AND SEX HORMONE BINDING GLOBULIN ON BRAIN AMYLOID BURDEN BETWEEN MALE AND FEMALE IN COGNITIVELY NORMAL ELDERLY POPULATION

      Background

      Although previous studies reported that sex hormones are associated with cognitive decline and increased risk for Alzheimer’s disease in elderly population, few studies investigated the association between sex hormones and brain beta amyloid protein (Aβ) deposition. In this study, we investigated the association between sex hormones and cerebral Aβ deposition in cognitively normal elderly population.

      Methods

      Through the Korean Brain Aging Study for Early Diagnosis and Prediction of Alzheimer’s Disease (KBASE), 117 cognitively normal elderly subjects (female 61, male 56) were included in this study. All the subjects underwent comprehensive clinical and neuropsychological assessment, 11C-labelled Pittsburgh Compound B (PiB) positron emission tomography (PET), and blood sampling. Global cerebral Aβ deposition was defined as mean cortical PiB retention of the cortical regions including the frontal, lateral temporal, lateral parietal and precuneus/posterior cingulate cortices. Plasma estradiol, testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH) and sex hormone binding globulin (SHBG) levels were measured. Calculated free estradiol and free testosterone index (FTI), which reflect the biologically active fraction of those hormones, were used for analyses. We performed Pearson’s correlation and linear regression analysis across the whole cohort, and also performed the subgroup analyses in each gender.

      Results

      For the entire subjects, we did not find any associations of sex hormones, gonadotropins, and SHBG with global PiB retention. However, subgroup analyses showed that FTI (β=-9.240, t=-2.92, p=0.005) and FSH (β=-0.128, t=-2.73, p=0.008) levels are associated with global PiB retention in female, while SHBG (β=0.187, t=2.75, p=0.008) level was related to global PiB retention in male.

      Conclusions

      These findings suggest that there might be gender-specific differences in the way how sex hormones and gonadotropins affect cerebral Aβ deposition.