Aims: Low circulating T in older men is associated with many health problems. We compared cross-sectional and longitudinal analyses of hormones and morbidity in the CHAMP cohort to deduce the direction of causality.
Methods: The population-based CHAMP cohort of men aged 70 years and older were assessed at baseline (n=1705), 2-year (n=1367) and 5-year (n=958) follow-up. At each visit, serum T, dihydrotestosterone (DHT), estradiol (E2) and estrone (E1) were measured by liquid chromatography-tandem mass spectrometry and related cross-sectionally or longitudinally using general estimating equations to self-rated health, quality of life, functional disability, muscle mass and strength, metabolic syndrome, sexual function, bone mineral density, falls and fractures, and cognitive function.
Results: Cross-sectionally, low serum T, DHT, E2 and E1 were associated with most outcomes. Longitudinally, low baseline serum T and E2 predict increased functional disability but no other studied health outcomes whereas low baseline serum E1 predicted deterioration in self-rated health, functional abilities and bone loss. However, a decline in serum T (<10%) or E1 was significantly associated with declines in sexual and cognitive functions over time. As placebo-controlled trials show that (a) the decrease in serum T is too small to explain the decrease in sexual function1-2 and (b) testosterone treatment does not improve cognitive function3. The decrease in circulating T is more likely to result from, rather than cause, reduced sexual function or cognition.
Conclusions: These findings from a large representative group of older Australian men suggest that declines in serum T levels may be a consequence, rather than a cause, of poor health in older men. Further studies are warranted to investigate serum E1 in men as an important novel health biomarker.