A systematic review of the relationship between impulsivity and violence in persons with psychosis: Evidence or spin cycle?

Individual differences in impulsive traits have been associated with a number of deviant behaviors, and impulsivity has been assumed to play a critical role in the manifestation of violent and other criminal behavior. Despite frequent citations of a positive association between impulsivity and violence in persons with psychosis, conflicting findings in the research literature elicited this systematic review. The main aims were to examine the empirical evidence of the association and to determine whether the research design and measurement used were sufficient for testing a possible causal relationship. Two types of empirical evidence were searched for in keeping with the traditional trait-state dichotomy: documentation of the direct impact of impulsivity on carrying out the violent act (state), and documentation of elevated levels of impulsivity in a person and increased occurrence of violent acts (trait). Searches that were conducted in six databases resulted in one study that supported the association and three that did not. Only 2 out of 22 estimates obtained from bivariate analysis indicated evidence of an impulsivity-violence link No single study had a design that yielded data on a direct impact of impulsivity on carrying out the violent act (i.e., the state aspect of the association). (C) 2013 Elsevier Ltd. All rights reserved.