Substance Use and Violence : Influence of Alcohol, Illicit Drugs and Anabolic Androgenic Steroids on Violent Crime and Self-directed Violence

Abstract: Interpersonal violence and suicide are major health concerns, leading to premature death, extensive human suffering and staggering monetary costs. Although violent behaviour has multiple causes, it is well known that acute substance intake and abuse increase the risks of both interpersonal and self-directed violence. This association is quite well established for alcohol, while a more ambiguous literature exists for other common drugs of abuse. For example, anabolic androgenic steroids (AAS), synthetic analogues to the “male” sex hormone testosterone are suggested to elicit violent and aggressive behaviour. Two studies (I and III) in the present thesis addressed the association between AAS use and being suspected or convicted of a violent crime among remand prisoners and in a general population sample, respectively. Further, using the case-crossover design to control for confounders stable within individuals, I also investigated the triggering (short-term risk) effect of alcohol and drugs such as benzodiazepines and AAS, on violent crime (Study II). Finally, a fourth study (IV) based on a large national forensic sample of suicide completers (n=18,894) examined the risk of using a violent, more lethal, suicide method, when under acute influence of alcohol, central stimulants or cannabis.The results of this thesis suggested that AAS use in itself is not a proximal risk factor for violent crime; the observed risk is probably due to the co-occurrence of abuse of other substances. Alcohol is a strong triggering risk factor for violent crime, constant across males and females as well as individuals with or without behavioral and psychiatric vulnerability. Intake of high doses of benzodiazepines is associated with an increased risk for violent crime. Cannabis use is associated with an increased risk of using the lethal suicide method of jumping from a height. I conclude that mapping substance abuse patterns may inform violence risk assessment and treatment planning.