Abstract
Objective
To examine psychosisโlike symptoms in users of legal and illicit drugs.
Methods
Schizotypal Personality Questionnaire (SPQ) scores were compared in groups of people with different exposure to cannabis, with the use of other drugs serving as a covariate. Supplemental analyses compared users of legal and illicit drugs with cannabis use as a covariate.
Results
Weekly (nโ=โ111) and monthly (nโ=โ136) cannabis users had higher scores on the SPQ than former (nโ=โ143) and nonโusers (nโ=โ81). The use of other drugs accounted for the links between cannabis and schizotypy. Lifetime use of psychomotor stimulant drugs plus ecstasy accounted for associations between cannabis and scores on the SPQ and its different subscales. Dividing groups by type of drug use revealed that those who used only cannabis and legal drugs (CLDs) (nโ=โ126) were no different from those who used only legal drugs (LDs) (nโ=โ74) but both groups scored significantly lower on the SPQ than polydrug users (nโ=โ247). When controlling for marijuana use in the last month, the significant difference across drug use groups remained.
Conclusions
The results suggest that research on marijuana and schizotypy requires careful assessment of the use of other drugs, especially psychomotor stimulants and ecstasy. Copyright ยฉ 2008 John Wiley & Sons, Ltd.