The best evidence available says no, at least not for men with normal age-related memory changes. The largest randomized controlled trial ever run on this question, the NIH-funded Testosterone Trials (TTrials) Cognitive Function Trial, gave hundreds of men with low testosterone either testosterone gel or a placebo for one year and found no meaningful difference in memory, executive function, or spatial ability between the two groups (Resnick SM, et al., JAMA, 2017). That result sits alongside a separate, well-documented pattern: men with lower testosterone levels are more likely to develop dementia later in life. Both things are true at once, and untangling why is the point of this article.
What Does the Best Evidence Actually Show?
The Testosterone Trials Cognitive Function Trial enrolled 493 men aged 65 and older with low testosterone and self-reported memory concerns, a group researchers call "age-associated memory impairment." Half received testosterone gel, half received a placebo gel, and neither group knew which they were getting. After 12 months, the men on testosterone showed no significant improvement over placebo on any of the six cognitive domains tested, including verbal memory, visual memory, and executive function (Resnick SM, et al., JAMA, 2017). A separate 36-month trial in a different cohort of older men reached a similar conclusion, finding no measurable cognitive advantage from testosterone treatment over standard care (Yeap BB, et al., "Testosterone, cognitive decline and dementia in ageing men," 2022).
In plain terms, the highest-quality studies to date have not found that giving testosterone to older men with normal age-related low levels sharpens their memory or thinking.
Why Do Low Testosterone and Dementia Risk Seem Linked, Then?
This is where the picture gets more nuanced. Multiple large observational studies have found that men with lower circulating testosterone are more likely to be diagnosed with dementia, including Alzheimer's disease, years later. A 2022 review pooling this evidence found that men in the lowest quintile of testosterone had a notably higher incidence of dementia compared to men with higher levels (Yeap BB, et al., 2022). A 2025 cohort study reached a similar conclusion, linking declining testosterone concentrations over time to a greater risk of cognitive impairment in aging men (Climacteric, 2025).
The catch is that observational data like this shows association, not cause and effect. Low testosterone could be a marker of the same underlying aging and disease processes that also drive cognitive decline, rather than a direct cause of it. It is also possible that early, undiagnosed dementia itself lowers testosterone through changes in the hypothalamic-pituitary axis, meaning low T shows up as an early symptom rather than a trigger. Randomized trials like the TTrials Cognitive Function Trial are designed specifically to cut through that ambiguity, and so far they have not confirmed that restoring testosterone reverses or slows the cognitive decline that observational studies associate with low levels.
Has Any Study Shown a Cognitive Benefit From TRT?
Some smaller and shorter studies have reported modest improvements in specific measures, like spatial cognition or processing speed, particularly in men who started with clinically low testosterone and clear hypogonadal symptoms rather than normal age-related decline (Bianchi VE, "Impact of Testosterone on Alzheimer's Disease," 2022). But these findings have been inconsistent across trials, and the largest, best-controlled study to date, the TTrials Cognitive Function Trial, did not replicate a memory benefit even over a full year of treatment. Reviewers generally consider the overall evidence too mixed and too short in duration to support TRT as a cognitive treatment or prevention strategy on its own.
What About Newer Safety Data From TRAVERSE?
The 2023 TRAVERSE trial, the largest cardiovascular safety study of TRT ever conducted, was not primarily designed to test cognition, but it reinforced the broader picture that testosterone's effects on the brain and body need to be evaluated on their own merits rather than assumed. Our breakdown of the TRAVERSE trial covers what that study found on cardiovascular risk, which is a useful companion read if you're weighing the overall risk-benefit picture of starting treatment.
