Testosterone treatment enhances regional brain perfusion in hypogonadal men

The positive effect of testosterone replacement therapy on psychosocial well-being in hypogonadal men has been demonstrated by various psychometric tests. However, there is no report available that objectively demonstrates the effect of testosterone on the function of the central nervous system in men. In this report we studied cerebral perfusion in seven hypogonadal men on testosterone replacement therapy. The blood perfusion to the central nervous system was assessed using single-photon emission-computed tomography. (99 m)Tc-hexamethyl-propylene-amine oxime crosses the blood brain barrier and localizes in brain tissue, depending on the intensity of the local blood flow. Psychosocial well-being was assessed with an Androgen Deficiency in Aging Men questionnaire. The study demonstrated that testosterone replacement enhanced cerebral perfusion in midbrain and superior frontal gyrus (Brodman area 8) at 3-5 wk of treatment. At 12-14 wk the study continued to show increased perfusion in midbrain in addition to the appearance of a new activated region in the midcingulate gyrus (Brodman area 24). The results of this study provide objective evidence that testosterone and /or its metabolites increased cerebral perfusion in addition to the improvement in cognitive function.