Alcohol confounds relationship between cannabis misuse and psychosis conversion in a high-risk sample

Acta Psychiatrica Scandinavica, January 2015

Cannabis use has been examined as a predictor of psychosis in clinical high-risk (CHR) samples, but little is known about the impact of other substances on this relationship.

Substance use was assessed in a large sample of CHR participants (N = 370, mean age = 18.3) enrolled in the multisite North American Prodrome Longitudinal Study Phase 1 project. Three hundred and forty-one participants with cannabis use data were divided into groups: No Use (NU, N = 211); Cannabis Use without impairment (CU, N = 63); Cannabis Abuse/Dependence (CA/CD, N = 67). Participants (N = 283) were followed for ≥2 years to determine psychosis conversion.

Alcohol (45.3%) and cannabis (38.1%) were the most common substances. Cannabis use groups did not differ on baseline attenuated positive symptoms. Seventy-nine of 283 participants with cannabis and follow-up data converted to psychosis. Survival analysis revealed significant differences between conversion rates in the CA/CD group compared with the No Use (P = 0.031) and CU group (P = 0.027). CA/CD also significantly predicted psychosis in a regression analysis, but adjusting for alcohol use weakened this relationship.

The cannabis misuse and psychosis association was confounded by alcohol use. Non-impairing cannabis use was not related to psychosis. Results highlight the need to control for other substance use, so as to not overstate the cannabis/psychosis connection.

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Specialist substance misuse treatment for young people in England 2013-14

Public Health England, January 2015

This paper reports on the statistics for children and young people using alcohol and drugs, the numbers attending specialist substance misuse services in 2013-14 and the outcomes.

The headlines:
• 19,126 young people received help for alcohol or drug problems
• 71% had cannabis as their main problem drug
• 79% of young people left services having successfully completed their

Click here to download the full report.