An Investigation of Aggression in Methamphetamine Users
MetadataShow full item record
Methamphetamine (MA) use is associated with increased aggression, though the specific mechanisms through which this association operates remain unclear. Research has demonstrated an association between MA, heightened impulsivity and reduced behavioural control. Similarly, there is strong evidence of a link between MA use and psychotic symptoms. Despite research efforts examining these independent associations, there is a paucity of studies examining how these factors interact to influence the relationship between MA use and aggression. Study 1 was conducted to examine the independent and combined roles of impulsivity and positive psychotic symptoms on the relationship between MA and aggression. In this study, 237 injecting MA users completed a range of self-report measures of hostility, impulsivity, and dependence. Higher levels of MA dependence were associated with increased hostility, higher levels of impulsivity and greater positive psychotic symptoms. Furthermore, the relationship between MA use and aggression was mediated by both impulsivity and positive symptoms of psychosis. Synergistic effects of impulsivity and positive psychotic symptoms on hostility were also observed, with substantially higher levels of hostility being associated with the presence of positive symptoms in conjunction with heightened impulsivity. The results of Study 1 are important in increasing our current understanding of the relationship between MA dependence and aggression, but the reliance on self-report measures does present a problem because of the susceptibility of such measures to report biases. Study 2 was therefore designed to extend previous research by exploring the relationship between MA and aggression using a behavioural measure of aggression, as well as self-report measures. Behavioural and self-report measures of impulsivity were also included. Results revealed that MA users, compared with non-MA users, not only reported higher levels of aggression, but they actually behaved more aggressively when competing with a (fictitious) opponent. Furthermore, some evidence of a dose-response relationship between MA and aggression was apparent. Unexpectedly, no group differences were evident on either the behavioural or self-report measures of impulsivity. Taken together, the present research attests to the robustness of the relationship between MA use and aggression, and points to the need for increased understanding of the complex and multifaceted nature of factors such as impulsivity and positive psychotic symptoms that contribute to this relationship.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Psychology
Item Access Status
Appendix "O", a published paper is not being published here.
Methamphetamine users and aggression