Activational effects of sex hormones on cognition in men.
BACKGROUND
Changing world demographic patterns, such as the increasing number of older people and the growing prevalence of cognitive impairment, present serious obstacles to preserving the quality of life and productivity of individuals. The severity of dementia varies from subclinical, mild cognitive impairment to neurodegenerative diseases such as Alzheimer's. In normally ageing men, these age-related cognitive declines are accompanied by gradual but marked decreases in androgen levels and changes in other hormone profiles. While developmental effects of sex hormones on cognition in the pre- and early postnatal period have been demonstrated, their activational effects in later life are still a focus of contemporary research. Although there is a plethora of published research on the topic, results have been inconsistent with different studies reporting positive, negative or no effects of sex hormones on various aspects of mental agility.


METHODS
This review summarizes the evidence supporting the biological plausibility of the activational effects of sex hormones upon cognition and describes the mechanisms of their actions. It offers a comprehensive summary of the studies of the effects of sex hormones on fluid intelligence in men utilizing elements from the Cochrane Collaboration Guidelines for Reviews. The results of both observational (cross-sectional and longitudinal) and interventional studies published to date are collated in table form and further discussed in the text. Factors contributing to the difficulties in understanding the effects of sex hormones on cognition are also examined.


CONCLUSIONS
Although there is convincing evidence that steroid sex hormones play an organizational role in brain development in men, the evidence for activational effects of sex hormones affecting cognition in healthy men throughout adult life remains inconsistent. To address this issue, a new multifactorial approach is proposed which takes into account the status of other elements of the sex hormones axis including receptors, enzymes and other hormones.
Ulubaev
A
A
Department of Endocrinology, Manchester Royal Infirmary, The University of Manchester, Manchester, UK. aslan.ulubaev@postgrad.manchester.ac.uk
Lee
D M
DM
Purandare
N
N
Pendleton
N
N
Wu
F C W
FC
D000728:Androgens / Q000378:metabolism; D000818:Animals; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate / Q000378:metabolism; D013196:Dihydrotestosterone / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D012739:Gonadal Steroid Hormones / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D011388:Prolactin / Q000378:metabolism; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism
D000728:Androgens; D012739:Gonadal Steroid Hormones; D012738:Sex Hormone-Binding Globulin; D013196:Dihydrotestosterone; D013739:Testosterone; D019314:Dehydroepiandrosterone Sulfate; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone