Low free testosterone levels are associated with prevalence and incidence of depressive symptoms in older men

Objective The prevalence of both low testosterone levels and depression increases with age. Currently, there is no consensus regarding the existence of an association. Our study analyses the cross-sectional association of testosterone levels with depressive symptoms and its prospective association with the development of incident depressive symptoms. Design Longitudinal population-based study; based on the data of the Longitudinal Aging Study Amsterdam (LASA) including 608 men aged ≥65 years (median age 75·6 years). Measurements Linear and logistic regression between total and free testosterone levels and depressive symptoms as measured by the Center of Epidemiologic Studies Depression (CES-D) scale, taking into account medical and lifestyle factors. Cox Proportional Hazards model was used to assess incident depressive symptoms. Results Unadjusted linear regression between square-root transformed CES-D scores and free testosterone levels showed a significant inverse association as a continuous variable (β = -0·10, P < 0·05), lowest quartile compared to highest (β = 0·12, P < 0·05) and with a threshold value of 170 pmol/l (β = 0·13, P < 0·05). The results remained significant for the group below threshold after adjustment for all confounders (β = 0·09, P < 0·05). Cox Proportional Hazards Model showed a decreased risk for incident depressive symptoms for men with higher free testosterone levels [HR = 0·997 CI (0·995-1·000)]. Men with the threshold value below 220 pmol/l were at increased risk of incident depressive symptoms [HR = 1·989 CI (1·173-3·374)]. Conclusions Free testosterone levels below 170 pmol/l are associated with depressive symptoms, while free testosterone levels below 220 pmol/l (lowest quintile of our population) predict the onset of depressive symptoms. © 2010 Blackwell Publishing Ltd.