The triggering effect of alcohol and illicit drugs on violent crime in a remand prison population: A case crossover study

Background: The association between substance abuse, particularly alcohol abuse, and violence has been well established. However, since substance abuse co-occurs with several other risk factors for violence, the causal link between substance abuse and violence and the extent to which the acute influence of alcohol, illicit drugs, benzodiazepines, and anabolic androgenic steroids have a triggering effect on violent behavior are more uncertain. Methods: Case-crossover design was used based on data from structured face to face interviews with remand prisoners (n = 194; 172 men, 22 women) suspected of violent crimes. Main outcome measure: odds ratio (OR 95% CI) for a violent crime, 24 h after exposure to different substances, compared to periods of no exposure was calculated using conditional logistic regression and a Mantel-Haenszel estimator with confidence intervals for sparse data. Results: Intake of alcohol (OR 6.41 CI 4.24-9.67) and large doses of benzodiazepines (OR 36.32 CI 7.14-183.65) triggered interpersonal violence. Stratified analyses of possible effect modifiers were sex, conduct/behavioral problems, trauma experiences; psychiatric vulnerability did not reveal any substantial differences. Conclusion: Influences of alcohol and unusually high doses of benzodiazepines are proximal risk factors for violent crime. Improved knowledge of short-term (and dose-related) risk factors may contribute to treatment planning and risk assessment of violence. (C) 2012 Elsevier Ireland Ltd. All rights reserved.