Androgens in Health and Disease.pdf - E Library

304 Cherrier and Craft
gesting that there may be brain structure changes related to previous findings of verbal
learning disabilities in these patients (126). In addition, patients who had never received
T treatment evidenced significant reductions in left temporal lobe gray matter compared
with those individuals who had received T supplementation. These findings suggest that
in addition to organizing effects on brain structure during development, androgens can also
affect neural structure and integrity throughout the human adult life-span.
SUMMARY
The studies reviewed in this chapter demonstrate a clear relationship between androgens
and specific aspects of cognition. Observed effects of androgens on cognition
may occur by several mechanisms, including direct effects of T or via T metabolites
such as DHT or estradiol. Androgens act via both classic receptor-mediated genomic
methods, as well as more recently characterized nongenomic methods. The temporal
relationship of androgen effects was reviewed, including organizational effects that
occur because of the presence of androgens during critical neural development periods
that result in permanent changes in behavior and cognition, as observed with CAH and
Klinefelter’s patients. Considerable evidence also suggests that androgens exert modulating
effects on cognition throughout the life-span, as demonstrated by observed
cognitive changes in transsexual individuals undergoing hormone treatment and older
adults receiving androgen supplementation. Taken together, there is strong support to
indicate that androgens exert effects on cognition and in particular spatial abilities.
Recent evidence from neuroimaging studies has extended our understanding of the
complex interactions between androgens and cognition to suggest that organizational
and activational effects of hormones interact with unique cognitive task demands and
their associated neural networks. This recent neuroimaging evidence may help explain
why androgens appear to have selective rather than widespread effects on cognition.
Clearly, more research is needed in this area, and future research endeavors will likely
further refine our understanding of these complex relationships.
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