Potent weed linked to psychosis

People who smoke high-strength marijuana every day are four times more likely to develop psychosis than those who have never used the drug, according to the largest-ever study on weed and mental health problems. As evidence grows of a link between marijuana and psychotic disorders, the new study suggests that levels of THC—the drug’s psychoactive component—are a major factor. Researchers from King’s College London looked at some 900 people in Europe and Brazil who received their first diagnosis of a psychotic disorder from 2010 to 2015 and compared them with more than 1,200 healthy people from the same regions. The scientists found that daily marijuana users were three times more likely to be diagnosed with psychosis than those who never consumed the drug, and four times more likely if they used cannabis with a high concentration of THC. Overall, the researchers estimate, 24 percent of new psychosis cases were linked to daily high-potency cannabis use. Co-author Robin Murray tells TheGuardian.com that the findings have implications for the debate over marijuana legalization. “Unless you want to pay for a lot more psychiatric beds,” he says, “you need to devise a system where you would legalize in a way that wouldn’t increase the consumption and increase the potency.”