An investigator at Flinders University in South Australia interviewed 30 patients aged between 18 and 65 who had a DSM-IV comorbid diagnosis of schizophrenia and cannabis 'abuse.' The investigator reported that over half of the respondents reported using cannabis to control schizophrenic symptoms. Of those interviewed, 25 patients reported that smoking cannabis reduced their anxiety; 21 patients said that marijuana helped them to forget childhood trauma; and 12 stated that cannabis "enhanc[ed] their spiritual awareness."

Ten respondents reported that cannabis "makes the voices louder and clearer;" eight patients said that pot "enhanced their cognitive processes;" and five stated that it "increased their physical or mental energy." Finally, eight patients said that the legalization of cannabis would "improve their mental state" because it would reduce the anxiety and paranoia associated with using an illegal drug.

Commenting on the study, NORML Advisory Board Member Dr. Mitch Earleywine, author of the book "Understanding Marijuana: A New Look at the Scientific Evidence," said that these patients' testimonials lend credibility to the theory that a large part of the association between marijuana and schizophrenia may be explained by self-medication.

"It's not that cannabis use is causing schizophrenia," he said. "It's that patients notice the initial symptoms of schizophrenia and turn to marijuana for relief."