Sex differences in overt aggression and delinquency among urban minority middle school students

suggest that the entry into adolescence might be a particularly vulnerable time for girls in terms of anger. Future studies need to replicate our findings that girls' anger increases during this time period, whereas boys' levels remain stable, as well as determine whether this difference is due to a developmental delay among boys and whether their levels of anger change at a later stage in development. Also studies are needed that examine the potential factors that may account for such sex differences in the transition to adolescence. For example, previously identified sex differences in the experiences of stressful life events (e.g., Brooks-Gunn, 1991 and Ge et al., 1994) or differences in the onset of puberty may account, in part, for different patterns of anger levels at this stage of development.

Previous studies that have examined sex differences in antisocial behaviors report conflicting results. Some studies have found remarkable similarities between males and females in the etiology and stability of antisocial behaviors (Connor et al., 2003, Herrera and McCloskey, 2001, Moffitt et al., 2001 and Williams et al., 2001) whereas others have found marked differences (Brennan et al., 2003, Broidy et al., 2003, LaGrange and Silverman, 1999 and Lewin et al., 1999). A recent criticism cites the lack of formal testing for sex differences in most studies (Moffitt et al., 2001); instead many studies run models separately for male and female participants and differences in significant p-values are reported and interpreted as evidence of sex-specific risk. Therefore many reported sex differences may not be robust. The current study highlights the importance of examining differences by sex in the developmental processes of antisocial behavior by formal tests of interaction effects rather than either analyzing the data separately or using sex as a control variable.

Although sex differences in the role of risk and protective factors in aggression and delinquency were not prevalent, these factors were important in the models tested, as expected. Engagement in baseline behaviors was the strongest predictor of all 7th grade behaviors, as would be expected. There were few differences by background characteristics, except for the consistent finding that being African American was associated with greater engagement in all aggressive and delinquent behaviors in the 7th grade. The second step in these models reflects the additional contribution of emotion (anger) and regulation (self-control), as well as a recent source of stress (family disruption) to aggression and delinquency after accounting for the expected, substantial continuity in these constructs. In the current study, anger and self-control were associated with both delinquency and aggression for both boys and girls. These findings are consistent with previous studies on the predictors of antisocial behavior among youth (Coie and Dodge, 1998, Cooper et al., 2003 and Loeber and Hay, 1997). However, family disruption was only associated with delinquency once anger and self-control were included. Going from a two-parent, non-blended household to any other family structure (single-parent, blended family or living in a no parent household) was associated with a significant increase in delinquency as compared to students not experiencing any family disruption. However, given that family disruption was only measured from 6th to 7th grade and no measures were available on previous changes in household structure or on how the change was experienced by the family, these results should be interpreted with caution. Future studies should include a measure of cumulative family disruptions and instability as well as other potential stressors (i.e., number of moves and school changes) to more fully examine sex differences in the associations between life stressors and the development of antisocial behaviors.

There are several other limitations to the present investigation. As indicated, the focus in this study was on urban, minority youth. As such, findings cannot be generalized to youth in suburban or rural communities. In addition, the measures in this investigation are self-reported in a survey format. Protocols were utilized to generate valid reporting of deviant behaviors but the protocol was still limited to the adolescent's self-report. Given that fairly high rates of aggressive and delinquent behaviors were reported, it does not seem that substantial under-reporting of deviant behaviors occurred. Finally, several studies have reported sex differences in the use of indirect or relational aggression (Crick, 1996, Crick, 1997 and Crick and Grotpeter, 1995) and there is recent debate over whether relational aggression is the “female aggression” (Hadley, 2004 and Underwood et al., 2001). Unfortunately because the larger prevention study did not include a focus on relational aggression we were not able to examine sex differences in this type of aggression within the current study. However the current study does support the need for prevention