Many studies have linked marijuana use with early onset of psychosis. The question is, does smoking marijuana cause earlier psychosis? A new review of 83 studies involving more than 22,000 participants seeks an answer. The meta-analysis found that people who smoked marijuana developed psychotic disorders an average 2.7 years earlier than people who did not use cannabis. But the review also found that people who used any illegal drug suffered psychosis two years earlier than non-users, not a large difference. While alcohol use was not associated with early onset, the studies reviewed could not rule out the influence of cigarette smoking, which is a common habit of people with psychotic disorders and those who smoke marijuana.  In many of the countries from which the data was gathered, in fact, cannabis is typically smoked mixed with tobacco. The researchers argue that cigarette smoking—unlike marijuana— does not worsen hallucinations or paranoia in patients with schizophrenia, so they believe that tobacco does not account for earlier onset. Led by Mathew Large of the University of New South Wales in Australia, the authors of the new research review also focused on other factors that may have contributed to the association between pot smoking and early psychosis in previous studies. For instance, it’s known that men are both more likely to take drugs and to develop psychosis at an earlier age than women, and the preponderance of men in past studies might have contributed to the connections found. It’s also known that young people, including those who have schizophrenia, are more likely to smoke pot than older folks, so previous studies that put upper age limits on their participants could have overstated the marijuana-psychosis link. But based on the meta-analysis, researchers found that the link persisted independently of these factors. In the paper, published in the Archives of General Psychiatry, they conclude that their results “provide evidence for a relationship between cannabis use and earlier onset of psychotic illness and they support the hypothesis that cannabis use plays a causal role in the development of … Continue reading Marijuana Linked with Earlier Onset of Schizophrenia in Research Review