Hormone replacement therapy and cognition in an Australian representative sample aged 60-64 years

Objective: To investigate the relationship between hormone replacement therapy (HRT) and level of cognitive performance intra-individual variability, and interactions with statin use, progesterone therapy and type of menopause. Methods: A representative sample of 60-64 year olds was recruited from the Canberra and Queanbeyan regions in Australia. They were administered tests of verbal memory, working memory, speed of information processing, simple and complex reaction time, verbal intelligence and the Mini-Mental State Exam. Intra-individual variation (consistency) on performance on simple and complex reaction time tasks was calculated. Women provided information on HRT use and demographic, health and lifestyle variables. Results: Four hundred and four (35.0%) current postmenopausal HRT users, 316 (27.4%) previous HRT users and 434 (37.6%) women who had never used HRT, were included in this study. There were significant overall differences between HRT current and previous users on age, prevalence of diabetes, alcohol use, body mass index, level of anxiety and lung function. After controlling for potentially confounding health and demographic variables, there were no significant main effects detected between HRT groups on any cognitive measure. Significant interactions were detected between HRT group and statin use on intra-individual variability on simple reaction time, and between HRT group and menopause type on intra-individual variability on choice reaction time. All other interactions were non-significant. Conclusions: HRT use had no effect on level of cognitive performance. Two interactions were detected between HRT use and statin use, and type of menopause on intra-individual variability. Given the large number of comparisons, little weight can be placed on these significant results.