Testosterone and mood in aging men.

Age-associated hypothalamic-pituitary-gonadal (HPG) axis hypofunction, or partial androgen deficiency of the aging male, is thought to be responsible for various age-associated conditions such as reduced muscle and bone mass, mobility limitations, frailty, obesity, sleep apnea, cognitive impairment, sexual dysfunction, and depression. It has been difficult to establish consistent correlations between these symptoms and plasma testosterone levels in middle-aged men, but testosterone replacement does lead to improved muscle strength, bone density, and sexual function. This article focuses on the relationship between testosterone and mood in older men, and the treatment of age-related depression with exogenous testosterone.