Hormonal predictors of healthy ageing in older men

Increasing life expectancy, coupled with declining fertility rates, has resulted in an ageing of the population. By 2050, nearly one quarter of the Australian population will be aged 65 years or older. The proportion of the population aged 85 years or older is expected to triple. Because the prevalence of chronic disease and disability increases with age, this demographic transition will pose substantial challenges. Age-related declines are observed in several important endocrine systems. In men, testosterone decreases across the lifespan, and there is debate as to whether declining levels of this hormone play a role in mediating many of the age-related changes in health and functional status that occur in old age. However, there have been few wellpowered epidemiological studies to date. The aim of this thesis was to explore whether endogenous testosterone levels were associated with adverse outcomes in several key domains, including cognition, frailty, cardiovascular disease, sexual function, and cancer. The study population comprised up to 3,638 community-dwelling men from Perth, Western Australia, participating in the longitudinal, population-based, Health in Men Study (HIMS). Testosterone, sex hormone-binding globulin, and luteinizing hormone were measured by immunoassay in a cohort of men aged 70 years or older. Outcome measures included memory (measured with the California Verbal Learning Test and Standardised Mini-Mental State Examination), frailty (assessed with the FRAIL scale, comprising questionnaire data and physical measures), mortality and cardiovascular events (assessed by electronic record linkage), sexual activity and sexual dysfunction (assessed by self-reported questionnaire), and incident cancer diagnoses (assessed by electronic record linkage). Statistical techniques included linear and logistic regression, and Cox and competing-risks proportional hazards models.