Mood changes, body mass index and bioavailable testosterone in healthy men:: results of the Androx Vienna Municipality Study

To determine whether sex hormones alone or in combination with body mass index (BMI) influence mood in men. Blood samples were taken from 669 manual workers (aged 43-67 years) to measure sex hormone levels, in particular bioavailable testosterone (BAT). At the same time BMI was calculated. All participants completed the Beck's Depression Inventory (BDI) for the evaluation of depression. Then BMI and BAT were correlated to the BDI scores, to determine a possible interaction. There was a quadratic main effect for BAT on the BDI scores, i.e. an increased risk of depression with an odds ratio of 1.871 (P = 0.029) for hypo- and hypergonadal men. Also, there was an interaction between BAT and BMI, which was mainly detected in underweight and obese men. This U-shaped effect for underweight and obese men was not detected in men with a 'normal' weight, who had a significantly linear decrease in the risk of depression by changing from the hypogonadal to the eugonadal subgroup, as well as for changing from the eugonadal to the hypergonadal subgroup, with a mean odds ratio of 0.513 (P = 0.032). Depression depends on BAT and BMI; in men of normal weight, an increase in BAT reduces the risk of depression, which is not the case in underweight and obese men. Consequently eugonadal men with normal testosterone levels have the lowest risk of depression.