Testosterone, androgen receptor gene CAG repeat length, mood and behaviour in adolescent males

Objectives: Androgen activity has been implicated in a range of traits and behaviours that have well-documented sex differences. However, the results of the studies on the relationship between testosterone and these traits and behaviours are inconsistent. This study has analyzed i) whether CAG repeat length, a presumed modulator of androgen receptor sensitivity, is associated with sex-dimorphic traits and behaviours (aggressive and non-aggressive risk-taking (ART and NART), dominance, depressive symptoms and self-esteem), and ii) whether CAG repeat length interacts with free testosterone (FT) with respect to these traits and behaviours. Design and methods: Data obtained from a group of adolescent boys (n=301; mean age: 14.4 years) were analyzed using multivariate general linear modelling (SPSS, Chicago, IL, USA 15.0). Results: We found no direct correlation between CAG repeat length and dependent variables. We found significant interactions between CAG repeat length and testosterone, indicating that FT was more positively related to ART and NART with a shorter repeat length, and that an inverse association of FT with depressive symptoms and a positive association with self-esteem were stronger in boys with a longer CAG repeat length. Conclusion: Our findings indicate the importance of studying FT and CAG repeat length simultaneously with respect to sex-dimorphic traits, taking into account the possible interactions between the two.