Testosterone and cognition in elderly men: A single testosterone injectionblocks the practice effect in verbal fluency, but has no effect on spatialor verbal memory

Background: The relevance of the age-associated decline ill testosterone fo r cognition in elderly men is still poorly understood. One hypothesis is th at testosterone enhances spatial abilities, while it might impair verbal sk ills. Methods: Thirty elderly men received a single testosterone (250 mg testoste rone enanthate) or placebo injection. Cognitive performance nas tested befo re and 5 days after treatment using spatial as at ell as verbal rests. Results: Five days after injection, testosterone and estradiol levels rr er e still in the supraphysiologic range. In the verbal fluency task, fire pla cebo group, but not the testosterone group, showed a practice effect. There fore, the testosterone group performed significantly worse than the placebo group after treatment. Na effects of testosterone were observed in the oth er verbal and spatial tasks. Conclusions: The present finding, that testosterone blocks the practice eff ect in verbal fluency: partly supports the general idea that sex steroids m odulate performance in tests with known gender differences. Moreover it dem onstrates that these effects can occur rapidly, However, beneficial effects on spatial cognition or memory might need more time to develop and/or migh t only occur when a less pronounced testosterone increase is induced.