Why do we need a trial on the effects of testosterone therapy in older men?

Decreases in levels of sex hormones occur with aging. Observational studies have found associations of low testosterone concentrations in older men with adverse symptoms; however, these associations do not prove causality. Therefore, the question arises whether to treat older men whose serum testosterone is low. In 2009, the Testosterone Trial (T Trial) was funded to examine the efficacy of therapy in 800 elderly men with low testosterone levels; potentially associated symptoms; and abnormalities in physical, sexual, or cognitive function or vitality.