Age of Substance Use Onset as a Predictor of Early Adult Substance Dependence and Offending in Male and Female Delinquents: Simple and Mediated Moderation

This study was designed first, to test whether sex moderated the effect of substance use onset on early adult substance dependence and offending and second, to identify the factors responsible for this effect. Structured equation modeling with 1,281 adjudicated delinquents (1,104 males, 177 females) from the Pathways to Desistance study revealed that sex moderated the onset-substance dependence and onset-offending relationships. Whereas age of substance use onset predicted early adult substance dependence in both males and females, it only predicted early adult offending in males. Out of six putative mediators, only one, adolescent moral disengagement, satisfied the criteria for mediated moderation. Mediation of the moderated onset-offending relationship was the result of moral disengagement correlating with both age of substance use onset and early adult offending in male but not female delinquents. Moral disengagement displayed similar patterns of correlation in the onset-substance dependency relationship but failed to satisfy all criteria for mediated moderation.