Previous research has pointed to the possibility that some cases of depression could be successfully treated with testosterone replacement therapy. Now researchers have found a link between lower levels of testosterone and depression in older men. From Science Daily:
A total of 203 of the participants (5.1 percent) met criteria for depression; these men had significantly lower total and free testosterone levels then men who were not depressed. After controlling for other factors--such as education level, body mass index and cognitive scores--men in the lowest quintile (20 percent) of free testosterone concentration had three times the odds of having depression compared to men in the highest quintile [among depressed men].
The report continues:
The mechanism by which low hormone levels might affect depression risk has not been identified, but might involve changes in the levels of neurotransmitters or hormones in the brain, the authors note.
This unnecessarily assumes directionality in the relationship between between testosterone and depression. It could be that depression reduces testosterone or that reduced testosterone is part of a complex of interrelated symptoms. We should remember, as well, that non-depressed women function with far lower levels of testosterone than depressed men.
And, with the elevated risk of prostate cancer associated with testosterone therapy, physicians would be understandably reluctant to offer this treatment, particularly to younger men who could potentially face decades of such therapy.