Testosterone and cognitive function: current clinical evidence of a relationship

Abstract

Background: Testosterone levels decline as men age, as does cognitive function. Whether there is more than a temporal relationship between testosterone and cognitive function is unclear. Chemical castration studies in men with prostate cancer suggest that low serum testosterone may be associated with cognitive dysfunction. Low testosterone levels have also been observed in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). This paper reviews the current clinical evidence of the relationship between serum testosterone levels and cognitive function in older men. Methods: A systematic literature search was conducted using PubMed and EMBASE to identify clinical studies and relevant reviews that evaluated cognitive function and endogenous testosterone levels or the effects of testosterone substitution in older men. Results: Low levels of endogenous testosterone in healthy older men may be associated with poor performance on at least some cognitive tests. The results of randomized, placebo-controlled studies have been mixed, but generally indicate that testosterone substitution may have moderate positive effects on selective cognitive domains (e.g. spatial ability) in older men with and without hypogonadism. Similar results have been found in studies in patients with existing AD or MCI. Conclusions: Low endogenous levels of testosterone may be related to reduced cognitive ability, and testosterone substitution may improve some aspects of cognitive ability. Measurement of serum testosterone should be considered in older men with cognitive dysfunction. For men with both cognitive impairment and low testosterone, testosterone substitution may be considered. Large, longterm studies evaluating the effects of testosterone substitution on cognitive function in older men are warranted.

High testosterone levels and sensitivity to acute stress in perpetrators of domestic violence with low cognitive flexibility and impairments in their emotional decoding process: A preliminary study

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Are declining testosterone levels a major risk factor for ill-health in aging men?

“…In this context, trials of testosterone therapy in men to evaluate its effects on measures of cognitive function have shown mixed results. 36,37 Short-term hormonal therapy can induce measurable changes in cognitive performance in young men. 38 In a randomized, placebo-controlled crossover trial of 15 elderly men with baseline total testosterone 48.3 nmol l À1 (to convert to ng per 100 ml, divide value in nmol l À1 by 0.0347), intramuscular testosterone therapy resulted in decreased verbal memory, 39 whereas in men with Alzheimer's disease testosterone treatment appeared to improve quality of life as assessed by caregivers without impacting on measures of cognition.…”

Analysis of testosterone pulsatility in women with ovulatory menstrual cycles

“…It is well known that testosterone influence behavior and both cognitive and sexual function in men (35). However, evidence in women is limited by lack of normative data for androgen levels and much controversy relies about types of treatment.…”