Testosterone, Cortisol:Testosterone ratio and physical performance in later life: results from the Caerphilly Prospective Study (CaPS)

Introduction: Testosterone levels fall with age hence men with higher levels may show better physical performance in later life, though current evidence is inconsistent. An elevated cortisol to testosterone ratio has been associated with metabolic dysfunction and may reflect chronic stress. No previous study has looked at the cortisol to testosterone (C/T) ratio and physical performance in later life. We examined the relationship between total testosterone, C/T ratio and physical performance in later life. Methods: Middle-aged men (45-59 years) were recruited between 1979 and 1983 as part of the Caerphilly Prospective Study and had cortisol and testosterone measured from morning fasting serum. They were followed up for approximately 20 years and then had their walking speed and balance time measured. 748 and 848 participants had data on C/T ratio and testosterone respectively and physical performance measures. Results: Higher morning testosterone was associated with faster walking speed (0.56 metres/min, 95% CI 0.05, 1.07; age-adjusted), though this was attenuated when fully adjusted (0.38 metres/min, 95% CI -0.19, 0.95). Higher testosterone was weakly associated with the worst quintile of balance (odds ratio 0.91, 95% CI 0.77, 1.08). There was no evidence of an association between C/T ratio measures and either walking speed or balance. Conclusion: Higher total testosterone in mid-life was associated with faster walking speed in later life but this was not seen with the C/T ratio. These findings provide limited support for a role of testosterone levels in maintenance of mobility in older age but require replication in further studies.