Older men with low levels of free testosterone have a higher prevalence of depression, according to a report in the March Archives of General Psychiatry. Study authors added that the association cannot be adequately explained by physical comorbidity.

Osvaldo P. Almeida, MD, PhD, and colleagues surveyed 3,987 men (ages 71 to 89) from the community of Perth, Western Australia. Between 2001 and 2004, the men completed questionnaires that included items assessing demographic and clinical information. Participants also underwent testing for depression and cognitive difficulties. Information on physical health conditions was obtained through a short survey and a national health database. Blood samples were drawn and analyzed for total testosterone and free testosterone.

A total of 203 men (5.1%) met diagnostic criteria for depression. Participants with depression had significantly lower total and free testosterone concentrations than did nondepressed men. The depressed men, however, were also more likely to smoke, have low educational attainment, be obese, have Mini-Mental State Examination scores less than 24, have a history of antidepressant use, and have greater concurrent physical morbidity. After adjusting for these factors and for age, men with depression were 1.55 and 2.71 times more likely to have total and free testosterone concentrations, respectively, in the lowest quintile. “When the concentration of free testosterone is lower than 6 ng/dL, the risk of depression increases threefold compared with men with concentrations greater than 10 ng/dL,” the researchers reported.

The mechanism by which low hormone levels might affect depression risk has not been identified, the researchers noted, but they speculated that it might involve changes in the levels of neurotransmitters or hormones in the brain.

Dr. Almeida, a Professor of Old Age Psychiatry at the University of Western Australia, and colleagues concluded that “a randomized controlled trial is required to determine whether the link between low free testosterone level and depression is causal because older men with depression may benefit from systematic screening of free testosterone concentration and testosterone supplementation.”

Suggested Reading
Almeida OP, Yeap BB, Hankey GJ, et al. Low free testosterone concentration as a potentially treatable cause of depressive symptoms in older men. Arch Gen Psychiatry. 2008;65(3):283-289.

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