Testosterone supplementation improves spatial and verbal memory in healthyolder men

Objective To determine the relationship between exogenous testosterone admi nistration and cognitive abilities in a population of healthy older men. Ba ckground: Serum levels of total and bioavailable testosterone gradually dec rease with age in men and are associated with reductions in muscle mass, os teoporosis, decreased sexual activity, and changes in cognition. Methods: T wenty-five healthy, community-dwelling volunteers, aged 50 to 80 years, com pleted a randomized, double-blind, placebo-controlled study. Participants r eceived weekly intramuscular injections of either 100 mg testosterone enant hate or placebo (saline) for 6 weeks. Cognitive evaluations were conducted at baseline, week 3,and week 6 of treatment by use of a battery of neuropsy chologic tests. Results: Circulating total testosterone was raised an avera ge of 130% from baseline at week 3 and 116% at week 6 in the treatment grou p. Because of aromatization of testosterone, estradiol increased an average of 77% at week 3 and 78% at week 6 in the treatment group. Significant imp rovements in cognition were observed for spatial memory (recall of a walkin g route), spatial ability (block construction), and verbal memory (recall o f a short story) in older men treated with testosterone compared with basel ine and the placebo group, although improvements were not evident for all m easures. Conclusions The results suggest that shortterm testosterone admini stration enhances cognitive function in healthy older men. However, it rema ins unclear whether these improvements in cognition are attributable to inc reased testosterone or estradiol levels, or both. The potential role of tes tosterone vs its metabolites on cognition requires further research.