Continuity of cannabis use and violent offending over the life course.

BACKGROUND: Although the association between cannabis use and violence has been reported in the literature, the precise nature of this relationship, especially the directionality of the association, is unclear. METHOD: Young males from the Cambridge Study of Delinquent Development (n = 411) were followed up between the ages of 8 and 56 years to prospectively investigate the association between cannabis use and violence. A multi-wave (eight assessments, T1-T8) follow-up design was employed that allowed temporal sequencing of the variables of interest and the analysis of violent outcome measures obtained from two sources: (i) criminal records (violent conviction); and (ii) self-reports. A combination of analytic approaches allowing inferences as to the directionality of associations was employed, including multivariate logistic regression analysis, fixed-effects analysis and cross-lagged modelling. RESULTS: Multivariable logistic regression revealed that compared with never-users, continued exposure to cannabis (use at age 18, 32 and 48 years) was associated with a higher risk of subsequent violent behaviour, as indexed by convictions [odds ratio (OR) 7.1, 95% confidence interval (CI) 2.19-23.59] or self-reports (OR 8.9, 95% CI 2.37-46.21). This effect persisted after controlling for other putative risk factors for violence. In predicting violence, fixed-effects analysis and cross-lagged modelling further indicated that this effect could not be explained by other unobserved time-invariant factors. Furthermore, these analyses uncovered a bi-directional relationship between cannabis use and violence. CONCLUSIONS: Together, these results provide strong indication that cannabis use predicts subsequent violent offending, suggesting a possible causal effect, and provide empirical evidence that may have implications for public policy.

Violent responses to strain: an examination of conditioning influences.

Past research on General Strain Theory (GST) has not widely examined the application of the theory for understanding violent responses to strain. Additionally, the theory suggests there may be varying effects of strain on possible deviant outcomes across individuals differentiated on their dispositions toward deviance. In the current analysis, we examine violent responses to strain using original data collected from a sample of college-aged youth. Moreover, we specifically examine whether the effects of strain and anger on possible violent outcomes are invariant across individuals differentiated on their level of exposure to deviant peers and moral constraints against deviance. Using structural equation modeling, our results suggest that a composite measure of strain increases respondents' intentions to engage in assaultive behavior net of other predictors. Additionally, the results reveal that anger mediates the impact of strain on possible violent responses. Finally, the results of our subgroup analyses suggest that the basic form of the GST model is invariant across groups.