is a cross-tabulation of the initial and Year 2 measures of physical and relational aggression group status. Results show a relatively strong correspondence between behaviors across the 2-year period, as well as some changes over time in group status. The large majority of nonaggressive youth remained nonaggressive at first follow-up (84.2%). However, a small percentage of these nonaggressive youth became physically aggressive in Year 2 (4.1%); 10.3% of nonaggressive youth became relationally aggressive; and 1.3% of youth became both physically and relationally aggressive a year later. Those who were physically aggressive at the start were somewhat more divided among the other groups in Year 2, including 43.6% of youth who reported no subsequent aggression. Over half of the youth in the Year 1 physical aggression group either remained physically aggressive (40.0%) or transitioned to physical and relational aggression combined (12.7%). Relatively few adolescents who were physically aggressive in Year 1 changed to being only relationally aggressive the following year (3.6%). Of those who were relationally aggressive initially, half (50.4%) became nonaggressive and just over a third (34.4%) continued as relationally aggressive. Smaller percentages of the relationally aggressive youth moved to physical aggression only or combined with relational aggression (6.3% and 8.9%, respectively). Finally, of the youth who were both physically and relationally aggressive in Year 1, 31.1% later became nonaggressive; 27.9% transitioned to relational aggression alone; 21.3% continued with both behaviors; and 19.7% were only physically aggressive 1 year later. These differences in group status over the 1-year period are statistically significant overall (χ2 (9) = 488.82, p < .001).
Cross-Tabulation of Group Status Variables
Findings in correspond to tests of initial group status in Year 1 and later physical and relational aggression in Year 2. However, here, demographics and the three promotive variables of family attachment, school commitment, and academic achievement were added to the analysis. Year 1 aggression was modeled as a series of group comparisons: physical aggression versus no aggression; relationally aggression versus no aggression; and physical and relational aggression versus no aggression. Consistent with the results of , there is continuity in aggressive behavior over the 1-year time period. After accounting for all other variables in the model, physical aggression in Year 1 was a strong, significant predictor of physical aggression in Year 2 (OR: 15.26). Similarly, Year 1 relational aggression predicted Year 2 relational aggression (OR: 5.81). Year 1 physical aggression did not, however, predict Year 2 relational aggression; yet, Year 1 relational aggression did significantly predict later physical aggression (OR: 3.17). The combination of physical and relational aggression in Year 1 predicted both outcomes of physical and relational aggression in Year 2 (ORs: 8.64 and 7.56, respectively). For relational aggression as an outcome, the combined behaviors in Year 1 were more strongly predictive than the behavior by itself.
Prediction of Year 2 Physical and Relational Aggression--Full Sample
Tests of the three promotive factors resulted in significant main effects for family attachment and relational aggression; for school commitment and physical aggression; and for academic achievement and physical aggression (academic achievement also appeared a significant predictor of relational aggression, although the association was in the opposite direction; the bivariate correlation of these variables was nonsignificant, suggesting this is an anomalous finding).
In all, findings of and suggest that, while there is some evidence of behavior change from one type of aggression to the other, the more likely is a continuation of the same behavior, or a shift over time to nonaggression. While relational aggression may increase the risk of physical aggression, it appears less likely that physical aggression leads to relational aggression. Promotive effects differ according to the tested outcome and family attachment was the only significant predictor of relational aggression after accounting for all other variables.
In , results are given for the other Year 2 outcomes of recent binge drinking, past-year tobacco use, past-year marijuana use, past-year depression, and past-year self-harm. For the remaining analyses, a prior measure of the same outcome behavior was added to each model to account for chronic conditions that could confound the association between Year 1 aggression and later consequences.
Prediction of Year 2 Outcomes From Year 1 Aggression--Full Sample
Results of suggest there is relatively little effect on Year 2 outcomes of Year 1 aggression. Relational aggression predicted Year 2 binge drinking, increasing the odds of that outcome by 1.73 times. And, physical aggression predicted Year 2 marijuana use (OR: 1.77). All other adjusted effects of Year 1 aggression were nonsignificant.
The promotive variables of family attachment, school commitment, and academic achievement were significant, but generally inconsistent across outcomes. Here, school commitment was the only significant promotive variable in all models. High academic achievement predicted Year 2 tobacco use, marijuana use, and depression after accounting for all other variables. Family attachment was only uniquely predictive of Year 2 depression.
Prior measures of each outcome (e.g., Year 1 binge drinking for Year 2 binge drinking) were in all models the strongest predictors overall, with odds ratios that ranged from 2.60 for binge drinking to 16.55 times for past-year tobacco use. Older age was a predictor of Year 2 binge drinking and past-year marijuana use. For depression and self-harm, younger age increased risk. And, female gender uniquely predicted the likelihood of past-year depression. Race was not consistently associated with the outcomes under study.
Extended Longitudinal Analysis
To examine the extent to which results extend to Year 3 outcomes, analyses were conducted again using a reduced sample (seventh-grade cohort) for which data were available in all 3 years. Variables were defined the same as in Year 2, although self-harm was not assessed and, therefore, not included. Results for binge drinking, tobacco use, marijuana use, and depression are shown in . Results for aggression in Year 3 are reported in the text below but not tabled.
Prediction of Year 3 Outcomes from Year 1 Aggression--Middle Cohort Only
Consistent with prior analyses, results for Year 3 outcomes show a continuity in each form of aggression over time. Yet, here the risk of continued aggression was highest for those in Year 1 in the combined group. The odds of physical aggression as an outcome in Year 3 were nearly 4 times greater for youth who were physically aggressive in Year 1 (OR: 3.88) than for nonaggressives. The odds of later physical aggression were even higher for those in the combined physical and relational aggression group (OR: 5.68). For relational aggression as an outcome, the risk was again highest for those in the combined group (OR: 4.53), although those who were only relationally aggressive in Year 1 also were at risk (OR: 2.82). However, those who were physically aggressive alone in Year 1 were not at significantly greater risk for relational aggression in Year 3 when compared to nonaggressives. As for the promotive effects for physical aggression as an outcome, only academic achievement was a significant predictor. In the analyses of Year 3 relational aggression, none of the three hypothesized promotive factors was significant.
For the remaining Year 3 outcomes, some interesting differences from Year 2 emerged (). For example, while it did not predict Year 2 binge drinking, the combination of physical and relational aggression in Year 1 predicted Year 3 binge drinking (OR: 2.86). Relational aggression also predicted Year 3 binge drinking in the analysis (OR: 2.71), as it had in Year 2. Family attachment and school commitment both predicted a lower risk of later binge drinking, whereas only school commitment had been significant for that outcome previously.
For Year 3 tobacco use, Year 1 relational aggression was significant (OR: 2.44), although it had not been significant for tobacco use in Year 2. School commitment and high academic achievement were both significantly related to the outcome, which is consistent with the prior Year 2 analysis.
For Year 3 marijuana use and depression, there were no unique effects of Year 1 aggression, although physical aggression was a predictor of marijuana use at Year 2. Promotive effects of family attachment and school commitment were significant for marijuana use; and, family attachment predicted depression.
Continuity in Aggression and Year 3 Outcomes
A final set of exploratory analyses compared Year 3 outcomes for those who were physically and/or relationally aggressive in Years 1 and 2. Although numbers are small due to the reduced sample in Year 3, results show a trend toward worse outcomes (binge drinking, tobacco use, and marijuana use) for youth who were aggressive in both years. For example, of the 13 youth who were physically aggressive in both Years 1 and 2, six (46%) reported recent binge drinking in Year 3 (compared to 28% and 23% of youth who were physically aggressive in Year 1 or Year 2 only); 9 of 13 (69%) reported past-year tobacco use (compared to 28% and 33% of those who were physically aggressive in Year 1 or Year 2 only); and 8 of 13 (62%) reported past-year marijuana use (compared to 44% and 43% of those who were physically aggressive in Year 1 or Year 2 only). A similar pattern was shown for those who were relationally aggressive, although overall percentages of relationally aggressive youth who used substances in Year 3 were smaller when compared to those who were physically aggressive. For example, 13 of 41 (32%) youth who were relationally aggressive in the 2 prior years reported Year 3 binge drinking. This compares to 23% (12 of 52) of relationally aggressive youth in Year 1 only and 8% (7 of 88) of relationally aggressive youth in Year 2 only. A general pattern of worse outcomes also was shown for youth who were both physically and relationally aggressive in both years.
For past-year depression in Year 3, there was no apparent increase in risk associated with the continuity of aggression in Years 1 and 2, although numbers are again very small and hard to compare. An equal percentage of youth who were aggressive in one or both prior years were found to have been depressed in Year 3 (approximately 17%).