The principal active ingredient in marijuana causes transient schizophrenia-like symptoms ranging from suspiciousness and delusions to impairments in memory and attention, according to a Yale research study.
Lead author Dr. D. Cyril D'Souza, associate professor of psychiatry at the School of Medicine, says 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.
"... [T]his 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," he says. "Clearly, further work is needed to test this hypothesis."
D'Souza and his co-researchers administered various doses of delta-9-THC, the main active ingredient in cannabis, to subjects who were screened for any vulnerability to schizophrenia. Some subjects developed symptoms resembling those of schizophrenia that lasted approximately a half-hour to one hour. These symptoms included suspiciousness, unusual thoughts, paranoia, thought disorder, blunted affect, reduced spontaneity, reduced interaction with the interviewer, and problems with memory and attention. THC also induced euphoria and 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 findings of this study 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.
Co-authors included Dr. Edward Perry, Lisa MacDougal, Yola Ammerman, Yu-Te Wu, Gabriel Braley, Ralitza Gueorguieva and Dr. John Krystal of Yale, and Thomas Cooper of Columbia College of Physicians and Surgeons.
-- By Jacqueline Weaver
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