title: Continuity of cannabis use and violent offending over the life course.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Institute of Psychiatry,Psychology & Neuroscience,King's College London,London,UK.
authors.forename: T
authors.initials: T
authors.lastname: Schoeler
authors.affiliation: Institute of Psychiatry,Psychology & Neuroscience,King's College London,London,UK.
authors.forename: D
authors.initials: D
authors.lastname: Theobald
authors.affiliation: Division of Psychology and Language Science,University College London,London,UK.
authors.forename: J-B
authors.initials: JB
authors.lastname: Pingault
authors.affiliation: Institute of Criminology,University of Cambridge,Cambridge,UK.
authors.forename: D P
authors.initials: DP
authors.lastname: Farrington
authors.affiliation: College of Behavioral and Community Sciences,University of South Florida,Tampa,FL,USA.
authors.forename: W G
authors.initials: WG
authors.lastname: Jennings
authors.affiliation: School of Economics,Political and Policy Sciences,University of Texas at Dallas,Richardson,TX,USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Piquero
authors.affiliation: Forensic Psychiatry Research Unit,Queens Mary University of London,London,UK.
authors.forename: J W
authors.initials: JW
authors.lastname: Coid
authors.affiliation: Institute of Psychiatry,Psychology & Neuroscience,King's College London,London,UK.
authors.forename: S
authors.initials: S
authors.lastname: Bhattacharyya
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D015331:Cohort Studies; D003415:Crime / Q000706:statistics & numerical data; D057237:Criminals / Q000706:statistics & numerical data*; D006801:Humans; D007604:Juvenile Delinquency / Q000706:statistics & numerical data*; D016015:Logistic Models; D008131:London / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology*; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011446:Prospective Studies; D057566:Self Report; D014754:Violence / Q000706:statistics & numerical data*; D055815:Young Adult
keywords: Cannabis; epidemiology; violence; Δ-9-tetrahydrocannabinol