With the recreational use of Marijuana now legal in eight states including California and its medical use legal in many more states, it might be time to revisit Reefer Madness. We laugh at that 1936 film that claimed marijuana created psychotic addicts but there may have been some truth in that old movie. While there is no evidence that “the burning weed with its roots in hell” as marijuana is depicted in Reefer Madness causes users to become violent or insane, there is substantial evidence that marijuana usage can increase the risk of developing schizophrenia and other psychotic disorders.

The risk is particularly pronounced in adolescents who have a genetic susceptibility to schizophrenia. In a study conducted at the Sackler School of Medicine at Tel Aviv (Israel) University, researchers conducted experiments on mice that had a mutant gene indicating a genetic susceptibility to schizophrenia and on a control group of mice that were not susceptible. The mice were there exposed to THC. After exposure, the schizophrenia-susceptible mice exhibited behavioral and biochemical brain pathologies indicating a schizophrenic episode, while no similar indications presented in the non-susceptible mice. I am simplifying the research and findings but the upshot is that the researchers found that the clinical representation mimics a schizophrenic “first episode” in humans.

Now you might think, as I did, that this is one study and it was done on mice. But other studies, independent of the one conducted at Tel Aviv University, have confirmed these results. At Bristol University in England, researchers found that THC disrupted the brain activity in rats that is responsible for memory and decision-making leaving the rats no longer able to navigate a maze. The areas of the brain affected in this study are also the areas of the brain implicated in schizophrenia. The authors of the study, which was published in the Journal of Neuroscience, believe that there is a connection between abuse of marijuana, which causes the brain disruptions, and onset of schizophrenia. One U.K. study even estimated that if marijuana use were eliminated in the U.K., schizophrenia would decrease by 8%.

Researchers in the Netherlands, where recreational marijuana has been legal for many years, conducted a study on human subjects who were regular marijuana users. The study showed that the symptoms of schizophrenia got worse after using marijuana. According to the researchers, getting high on marijuana worsened schizophrenic hallucinations and can trigger schizophrenic symptoms in those individuals who are at risk.

Recently, the Health and Medicine Division of The National Academies of Sciences, Engineering and Medicine issued a report after what was termed a “rigorous review” of the scientific research on the health effects of marijuana conducted since 1999. Among the numerous conclusions, the report noted that marijuana use is likely to increase the risk of developing schizophrenia as well as other psychological disorders…and the higher the usage, the higher the risk.

While all of these researchers note the need for additional studies, the evidence seems fairly solid that marijuana use presents a risk for individuals who are susceptible to schizophrenia, particularly adolescents, and may also trigger or exacerbate other mental illnesses. Marijuana may indeed have medical benefits but on the flip side, there is a danger that the increased use of marijuana among populations will aggravate or even cause mental illness.

Orange County criminal defense attorney William Weinberg is available to consult with you regarding any criminal matter. You can reach him at his Irvine office at 949-474-8008 or email him at