title: The impact of comorbid cannabis and methamphetamine use on mental health among regular ecstasy users.
abstract: OBJECTIVE
  Residual effects of ecstasy use induce neurotransmitter changes that make it biologically plausible that extended use of the drug may induce psychological distress. However, there has been only mixed support for this in the literature. The presence of polysubstance use is a confounding factor. The aim of this study was to investigate whether regular cannabis and/or regular methamphetamine use confers additional risk of poor mental health and high levels of psychological distress, beyond regular ecstasy use alone.
  
  
  METHODS
  Three years of data from a yearly, cross-sectional, quantitative survey of Australian regular ecstasy users was examined. Participants were divided into four groups according to whether they regularly (at least monthly) used ecstasy only (n=936), ecstasy and weekly cannabis (n=697), ecstasy and weekly methamphetamine (n=108) or ecstasy, weekly cannabis and weekly methamphetamine (n=180). Self-reported mental health problems and Kessler Psychological Distress Scale (K10) were examined.
  
  
  RESULTS
  Approximately one-fifth of participants self-reported at least one mental health problem, most commonly depression and anxiety. The addition of regular cannabis and/or methamphetamine use substantially increases the likelihood of self-reported mental health problems, particularly with regard to paranoia, over regular ecstasy use alone. Regular cannabis use remained significantly associated with self reported mental health problems even when other differences between groups were accounted for. Regular cannabis and methamphetamine use was also associated with earlier initiation to ecstasy use.
  
  
  CONCLUSIONS
  These findings suggest that patterns of drug use can help identify at risk groups that could benefit from targeted approaches in education and interventions. Given that early initiation to substance use was more common in those with regular cannabis and methamphetamine use and given that this group had a higher likelihood of mental health problems, work around delaying onset of initiation should continue to be a priority.
authors.affiliation: National Drug and Alcohol Research Centre, University of New South Wales, Sydney, Australia.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Scott
authors.forename: Amanda
authors.initials: A
authors.lastname: Roxburgh
authors.forename: Raimondo
authors.initials: R
authors.lastname: Bruno
authors.forename: Allison
authors.initials: A
authors.lastname: Matthews
authors.forename: Lucy
authors.initials: L
authors.lastname: Burns
mesh_terms: D000328:Adult; D000368:Aged; D019969:Amphetamine-Related Disorders / Q000150:complications*; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000150:complications*; D008603:Mental Health; D008694:Methamphetamine / Q000009:adverse effects*; D008875:Middle Aged; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000009:adverse effects*; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D057566:Self Report; D013315:Stress, Psychological / Q000139:chemically induced*; D055815:Young Adult
chemical_list: D008694:Methamphetamine; D018817:N-Methyl-3,4-methylenedioxyamphetamine