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Taken from WWW.pubmed.gov (testosterone studies)
Eur J Endocrinol. 2006 Dec;155(6):773-81.
Testosterone and cognitive function: current clinical evidence of a relationship.
Beauchet O.
Department of Geriatrics, Saint-Etienne University Hospitals, 42055 Saint-Etienne Cedex 2, France.
olivier.beauchet@univ-st-etienne.fr
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, long-term studies evaluating the effects of testosterone substitution
on cognitive function in older men are warranted.
PMID: 17132744 [PubMed - indexed for MEDLINE]
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