June 2004
Yale University researchers have shown that active ingredient in marijuana can cause transient schizophrenia-like symptoms ranging from suspiciousness and delusions to impairments in memory and attention in some patients. The study was an attempt to clarify a long known association between cannabis and psychosis in the hopes of finding another clue about the pathophysiology of schizophrenia.
Lead author D. Cyril D'Souza, M.D., is quoted in a Yale press release as saying "Just as studies with amphetamines and ketamine advanced the notion that brain systems utilizing the chemical messengers dopamine and NMDA receptors may be involved in the pathophysiology in schizophrenia, this study provides some tantalizing support for the hypotheses that the brain receptor system that cannabis acts on may be involved in the pathophysiology of schizophrenia."
The researchers administered various doses of delta-9-THC, the main active ingredient in marijuana, to subjects who were screened for any vulnerability to schizophrenia. Some subjects developed temporary symptoms similar to those of schizophrenia, usually lasting one half hour to one hour.
The symptoms included suspiciousness, unusual thoughts, paranoia, thought disorder, blunted affect, reduced spontaneity, reduced interaction with the interviewer, and problems with memory and attention. As expected THC also induced euphoria. A somewhat more surprising finding was increased levels of the stress hormone cortisol. There were no side effects in the study participants one, three and six months after the study.
The Yale researchers suggest that their go along with several other lines of evidence that suggest a contribution of cannabis and/or abnormalities in the brain cannabinoid receptor system to the pathophysiology of schizophrenia. Such research is in the very early stages, but it does back up clinical evidence that marijuana can cause paranoia and schizophrenic-like symptoms in some people. If schizophrenia runs in your family you should probably avoid marijuana.
Reference: Neuropsychopharmacology, Advanced Online Publication (June 2, 2004)
Last updated 11/5/2005
