A brain and mental health researcher is strongly arguing that there is no link between cannabis use and developing schizophrenia.
Matthew Hill, PhD of the University of Calgary's (Canada) Hotchkiss Brain Institute, writing in Nature, notes that there is no concrete evidence of a connection between cannabis and schizophrenia. As he points out, the incidence of schizophrenia has not gone up since the 1960s, when marijuana use became popular in the U.S. and Europe. In addition, countries in which a large segment of the population uses cannabis do not have higher schizophrenia rates.
However, Hill concedes that marijuana use might bring on schizophrenia earlier in those who are predisposed to the condition.
One of the first studies to indicate a link between marijuana and schizophrenia came out in 1987 in Sweden. It found Army soldiers who used cannabis were found to have a higher incidence of schizophrenia. However, Hill points out that the study found that high doses of THC, the active ingredient, can cause acute psychosis, which then goes away.
Many have mistakenly believed, he argues, that the psychosis is permanent. And no other studies have come to this conclusion.
A recent Harvard University study also found no association between cannabis use and schizophrenia.
Matthew Hill, of the University of Calgary’s Hotchkiss Brain Institute has published a Perspective piece in the journal Nature voicing his concerns about other academics and journalists who suggest that cannabis use causes schizophrenia. He points out that there is little evidence of such a connection and suggests that there is actually evidence that cannabis use does not cause the mental disorder.
Cannabis use has been in the news a lot of late, particularly in the U.S. where some states have made it legal to smoke marijuana—the common name for cannabis. But because it is a hot-button topic, some, particularly those opposed to its use, have taken to looking for reasons to stop the movement—and one of those arguments is that it causes schizophrenia. The problem with that, as Hill notes, is that no one has ever proved it to be true.