Adolescent boys' physical fighting and adult life outcomes: Examining the interplay with intelligence.

Although it is well known that adolescent delinquent behavior is related to poor outcomes in adulthood, longitudinal research on specific acts of delinquency and their interplay with important individual characteristics in predicting future outcomes is scarce. We aimed to examine how physical fighting-one of the most common acts of violent delinquency among adolescent boys-is related to adult life success in several domains, and how intelligence influences these associations. The study used data from 1,083 boys that participated in the population-based longitudinal Young in Norway Study, following adolescents from 1992 to 2015, by combining self-reports at four time points with comprehensive information from registers. Results showed that adolescent boys' physical fighting was associated with poor adult outcomes in the domains of employment, education, and criminal behavior. Associations remained significant even after controlling for conduct problems in general-which isolated the effects of fighting from other delinquent acts-as well as from a variety of other potential confounders. Detailed analyses on the interplay of physical fighting and intelligence showed that some parts of the associations between adolescent boys' fighting and several adverse adult outcomes could be ascribed to lower intelligence among the fighters. Moreover, intelligence moderated the relationship between physical fighting and adult education. Adolescent fighting was not related to educational attainment among boys with high intelligence, whereas boys with lower intelligence experienced detrimental effects of adolescent fighting. The analyses show the importance of considering adolescent boys' physical fighting as a potential risk factor for future social marginalization.