Testosterone, Digit Ratio, and Aggression Among Youth in Conflict with the Law in Kano, Nigeria

Abstract

Abstract Introduction: Studies have associated testosterone with aggression, although with a weak and sometimes equivocal one. This study aimed to determine the correlation between testosterone and digit ratio (r2D:4D) using measures of aggression in youth in conflict with the law in Kano, Nigeria. Materials and Methods: This case–control study involves 48 youth aged 11–16 years in conflict with the law living in a remand home. The participants were divided into two groups based on the reported history of violent behavior. Serum total testosterone level was determined using an ELISA kit. Aggression was determined by the Buss–Perry Aggression Questionnaire, whereas r2D:4D was measured directly using a digital caliper. Independent-sample t test was used to determine differences in quantitative variables, while Pearson’s correlation analysis was used to determine the correlation. Results: The mean age of the participants is 15.23 years. Serum testosterone level was positively correlated with anger (r = 0.327, P = 0.023) among all participants and with physical aggression (r = 0.405, P = 0.032) among those with a history of violent behavior. However, r2D:4D did not correlate with aggression or serum testosterone. Testosterone explained 22% of variance in physical aggression and is a predictor of physical aggression (P = 0.046) among all study participants. Among those with a history of violent behavior, testosterone explained 41% of variance in physical aggression (P = 0.032); a 1 nmol increase in testosterone increases the physical aggression score by 0.41. Conclusion: testosterone level is positively correlated with anger and physical aggression in youth in conflict with the law in Kano, Nigeria, while the digit ratio is not.