Predictors of paranoia amongst regular methamphetamine users

LITERATURE REVIEW Use of methamphetamine is associated with considerable physical and psychological burden. Methamphetamine-induced psychosis has been recognised as having considerable impact on emergency services. The condition is characterised by severe paranoid ideation. Whilst much research has been carried out in the respective fields of paranoia and of methamphetamine-induced psychosis, little research has been conducted into the predictors of subclinical paranoia amongst regular methamphetamine users. Such research is important as it may lead to greater awareness amongst methamphetamine users of the precursors to clinical psychosis and aid health practitioners in the management of such cases. Biological models of paranoia implicate the role of excessive dopamine in the mesolimbic pathway. Use of methamphetamine leads to a substantial increase in synaptic dopamine levels along this pathway. It is likely that this action is responsible for the increased risk of paranoia and associated psychotic symptoms amongst methamphetamine users. Existing literature suggests specific predictors of methamphetamine-induced psychosis include drug purity, dependence and concomitant cannabis use. Cannabis may contribute to paranoia via a unique, possibly non-dopaminergic, mechanism, further increasing the risk of psychosis amongst regular users of both drugs. Psychological models of paranoia vary but commonly implicate role of anxiety. Future research into the relationship between methamphetamine and paranoia should seek to identify the strongest predictors of paranoid ideation amongst regular methamphetamine users. EMPIRICAL STUDY Methamphetamine-induced psychosis places considerable burden on the individual and on broader society. Paranoia is a core symptom of this condition. The present study identifies several key variables that predict sub-clinical experience of paranoia within a population of methamphetamine users. Participants were 239 regular substance users who had consumed methamphetamine in the 6 months preceding interview. Participants were interviewed about their history of substance use and provided detailed demographic data. Levels of methamphetamine dependence, anxiety and paranoid ideation were assessed using the Severity of Dependence Scale, Kessler-10 Psychological Distress Scale (Kessler et al., 2002) and Paranoia Scale (Fenigstein & Vanable, 1992) respectively. Results indicate that anxiety is the strongest predictor of paranoia amongst the sample, accounting for 40% of the variance in the latent paranoia variable. In addition to anxiety, methamphetamine dependence, pre-existing mental health conditions and concomitant frequent cannabis use were all found to be significant predictors of paranoia after controlling for demographic variables. There is some evidence that methamphetamine purity, route of administration and frequency of use are also factors in the development of paranoid ideation. These findings are generally supportive of existing literature and have implications for the treatment of individuals who are dependent on methamphetamine or suffer elevated paranoia.