Highlights
- •What is the primary question addressed by this study?Among randomized clinical trials (RCTs) published in the last decade, does testosterone supplementation improve cognitive performance in cognitively healthy older men?
- •What is the main finding of this study?Comparison of placebo versus treatment group pre and post supplementation showed significant improvements in the treatment group for cognition as a whole, psychomotor speed and executive function, only in randomized clinical trials (RCTs) that demonstrate an increase in total testosterone levels after supplementation.
- •What is the meaning of the finding?Our results evidence the potential for testosterone supplementation to improve cognitive performance and support the differential effects of testosterone on individual cognitive domains.
ABSTRACT
Background
An increasing body of literature suggests a positive, neuroprotective effect for testosterone
on cognition in older men. However, randomized clinical trials (RCTs) examining the
effects of testosterone supplementation (TS) on cognitive function have been inconclusive.
Objective
To investigate the potential for TS to prevent cognitive decline in otherwise cognitively
healthy older men, by examining the differential effects of TS on cognitively healthy
older men in RCTs.
Methods
Comprehensive search of electronic databases, conference proceedings, and grey literature
from 1990 to 2018 was performed to identify RCTs examining the effects of TS on cognition
before and after supplementation, in cognitively healthy individuals.
Results
A final sample of 14 eligible RCTs met inclusion criteria. Using pooled random effects
expressed as Hedge's g, comparison of placebo versus treatment groups pre- and postsupplementation showed
improvements in the treatment group in executive function (g (11) = 0.14, 95% confidence interval [CI]: 0.03–0.26, z = 0.56, p = 0.011). However, it was noted that two studies in our sample did not
report a significant increase in mean serum total testosterone (TT) levels in the
treatment group after supplementation. Following exclusion of these studies, analysis
indicated improvement in the treatment group for the overall cognitive composite (g (11) = 0.18, 95% CI: 0.02–0.33, z = 2.18), psychomotor speed (g (3) = 0.22, 95% CI: 0.01–0.43, z = 2.07) and executive function (g (9) = 0.15, 95% CI: 0.03–0.28, z = 2.35). No significant differences were noted for the global cognition, attention,
verbal memory, visuospatial ability or visuospatial memory domains.
Conclusion
Overall, our findings support the potential for TS as a preventative measure against
cognitive decline, although the effect sizes were small. These findings warrant further
observational studies and clinical trials of good methodological quality, to elucidate
the effect of TS on cognition.
Key Words
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Article info
Publication history
Published online: May 20, 2019
Accepted:
May 7,
2019
Received in revised form:
May 7,
2019
Received:
November 30,
2018
Identification
Copyright
© 2019 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.
