title: Increased prevalence of self-reported psychotic illness predicted by crystal methamphetamine use: Evidence from a high-risk population.
abstract: The potential of methamphetamine, and high-potency crystal methamphetamine in particular, to precipitate psychotic symptoms and psychotic illness is the subject of much speculation internationally. Established psychotic illness is disabling for individuals and costly to society. The aim of this study was to investigate whether use of crystal methamphetamine was associated with greater prevalence of self-reported psychotic illness, compared to use of other forms of methamphetamine.
  
  
  
  The sample comprised participants interviewed as part of an annual cross-sectional survey of Australian people who inject drugs. 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.
authors.affiliation: National Drug and Alcohol Centre, UNSW Australia, 22-32 King St., Randwick, NSW 2031, Australia; Department of Psychiatry, UNSW Australia, Black Dog Institute, Hospital Road, Randwick, NSW 2031, Australia. Electronic address: j.lappin@unsw.edu.au.
authors.forename: Julia M
authors.initials: JM
authors.lastname: Lappin
authors.affiliation: National Drug and Alcohol Centre, UNSW Australia, 22-32 King St., Randwick, NSW 2031, Australia.
authors.forename: Amanda
authors.initials: A
authors.lastname: Roxburgh
authors.affiliation: National Drug and Alcohol Centre, UNSW Australia, 22-32 King St., Randwick, NSW 2031, Australia; Justice Health & Forensic Mental Health Network, NSW Health, P.O. Box 150, Matraville, NSW 2036, Australia.
authors.forename: Sharlene
authors.initials: S
authors.lastname: Kaye
authors.affiliation: National Drug and Alcohol Centre, UNSW Australia, 22-32 King St., Randwick, NSW 2031, Australia.
authors.forename: Jenny
authors.initials: J
authors.lastname: Chalmers
authors.affiliation: InforMH, Mental Health and Drug and Alcohol Office, NSW Health, P.O. Box 169, North Ryde, NSW 1670, Australia; Discipline of Psychiatry, Sydney Medical School - Northern Kolling Building Level 7, Royal North Shore Hospital, Reserve Road, St Leonards, NSW 2065, Australia.
authors.forename: Grant
authors.initials: G
authors.lastname: Sara
authors.affiliation: National Drug and Alcohol Centre, UNSW Australia, 22-32 King St., Randwick, NSW 2031, Australia.
authors.forename: Timothy
authors.initials: T
authors.lastname: Dobbins
authors.affiliation: National Drug and Alcohol Centre, UNSW Australia, 22-32 King St., Randwick, NSW 2031, Australia.
authors.forename: Lucinda
authors.initials: L
authors.lastname: Burns
authors.affiliation: National Drug and Alcohol Centre, UNSW Australia, 22-32 King St., Randwick, NSW 2031, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Farrell
mesh_terms: D000328:Adult; D019969:Amphetamine-Related Disorders / Q000150:complications / Q000523:psychology*; D001315:Australia / Q000453:epidemiology; D010054:Brief Psychiatric Rating Scale; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008694:Methamphetamine; D015995:Prevalence; D011605:Psychoses, Substance-Induced / Q000150:complications / Q000453:epidemiology* / Q000523:psychology; D012307:Risk Factors; D012309:Risk-Taking; D057566:Self Report
chemical_list: D008694:Methamphetamine
keywords: Crystal methamphetamine; Dependence; Drug-induced psychosis; Methamphetamine; Psychosis; Schizophrenia; Stimulant