Can low testosterone cause depression?

Low testosterone is associated with depressive symptoms in men, not necessarily major depressive disorder, but a cluster of low mood, anhedonia, reduced motivation, irritability, and cognitive slowing that is partially mediated by testosterone's effects on serotonin, dopamine, and norepinephrine neurotransmitter systems, and testosterone replacement in hypogonadal men with these symptoms produces measurable improvement in mood scores in multiple RCTs (Zarrouf et al., J Clin Psychiatry, 2009).

The clinical challenge is the overlap between hypogonadal mood symptoms and primary major depressive disorder (MDD). Both present with low mood, fatigue, and anhedonia. Treating MDD with TRT when the primary driver is serotonergic dysfunction produces limited benefit. Treating hypogonadism with antidepressants when the primary driver is testosterone deficiency is similarly suboptimal. Men presenting with depressive symptoms should have testosterone, thyroid function, CBC, and vitamin D tested as part of the evaluation, not as a substitute for mental health evaluation, but as an essential component of it.

Honesty Scale: Promising (2) for TRT improving mood in hypogonadal men with depressive symptoms. The effect size is variable and depends heavily on whether the depression is primarily testosterone-driven.

What to do: If you have been prescribed antidepressants for persistent low mood without a testosterone panel ever being drawn, request a morning testosterone, free testosterone, and SHBG test before your next prescription refill. The two conditions require different treatments and may both be present simultaneously.

For the full picture, read The Testosterone/TRT Deep Dive