Polydrug Use, Cannabis, and Psychosis-Like Symptoms
Nichalas T. Van Dam, Mitch Earleywine and Greg DiGiacomo, "Polydrug Use, Cannabis, and Psychosis-Like Symptoms," Human Psychopharmacology 2008 (published online ahead of print, Apr. 30, 2008)
Much of the purported link between marijuana use and psychosis is based on correlations between marijuana use and schizophrenia-like symptoms or traits, called "schizotypal personality." But this study suggests that the effects of other drugs also used by some who use marijuana may be confounding such findings: "Lifetime use of psychomotor stimulant drugs plus ecstasy accounted for associations between cannabis and scores on the SPQ [Schizotypal Personality Questionaire] and its different subscales. Dividing groups by type of drug use revealed that those who used only cannabis and legal drugs (CLDs) (n=126) were no different from those who used only legal drugs (LDs) (n=74) but both groups scored significantly lower on the SPQ than polydrug users (n=247)."
Free abstract and full text for a fee available at http://www3.interscience.wiley.com/journal/118935109/abstract
