Increased prevalence of self-reported psychotic illness predicted by crystal methamphetamine use: Evidence from a high-risk population.
The potential of methamphetamine, and crystal methamphetamine in particular, to precipitate psychotic symptoms has been the subject of much recent speculation. A recent paper by Professor Louisa Degenhardt and Dr Sarah Larney concluded that amphetamine-related harms, including hospital admissions for amphetamine psychosis (Degenhardt, Sara et al., 2016; NSW MoH, 2015), have increased in tandem with increased availability of high-potency crystal methamphetamine.
Using a sample of participants interviewed as part of an annual cross-sectional survey of Australian people who inject drugs – the Illicit Drugs Reporting System (IDRS) – the authors investigated whether use of crystal methamphetamine was associated with greater prevalence of self-reported psychotic illness compared to use of other forms of methamphetamine.
Comparisons were made between groups according to the nature of their methamphetamine use: crystal methamphetamine or other forms of methamphetamine. Self-reported diagnoses of psychotic illness and other mental health problems were compared between groups. Predictors of self-reported psychotic illness were examined using multivariable logistic regression analyses.
Self-reported psychotic illness was highly prevalent among users of crystal methamphetamine (12.0%), and significantly more so than among users of other forms of methamphetamine (3.9%) (OR = 3.36; CI: 1.03–10.97). Significant predictors of self-reported psychosis in the cohort were: use of crystal methamphetamine, dependent use, lack of education beyond high school and younger age.
Highly increased prevalence of self-reported psychotic illness is associated with use of high-potency crystal methamphetamine in people who inject drugs, particularly where there is dependent use. There is an urgent need to develop effective interventions for dependent crystal methamphetamine use, and a need to monitor for symptoms of psychotic illness in drug-using populations.