Effects of cannabidiol on schizophrenia-like symptoms in people who use cannabis

Br J Psychiatry. 2008 Apr;192(4):306-7. doi: 10.1192/bjp.bp.107.046649.


Cannabis contains various cannabinoids, two of which have almost opposing actions: Delta9-tetrahydrocannabinol (Delta9-THC) is psychotomimetic, whereas cannabidiol (CBD) has antipsychotic effects. Hair samples were analysed to examine levels of Delta9-THC and CBD in 140 individuals. Three clear groups emerged: ;THC only', ;THC+CBD' and those with no cannabinoid in hair. The THC only group showed higher levels of positive schizophrenia-like symptoms compared with the no cannabinoid and THC+CBD groups, and higher levels of delusions compared with the no cannabinoid group. This provides evidence of the divergent properties of cannabinoids and has important implications for research into the link between cannabis use and psychosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Analysis of Variance
  • Cannabidiol / analysis*
  • Delusions / psychology
  • Dronabinol / analogs & derivatives*
  • Dronabinol / analysis
  • Female
  • Hair / chemistry*
  • Humans
  • Male
  • Marijuana Abuse / diagnosis*
  • Marijuana Abuse / psychology*
  • Predictive Value of Tests
  • Psychoses, Substance-Induced / diagnosis*


  • Cannabidiol
  • delta9-tetrahydrocannabinol hemisuccinate
  • Dronabinol