Study: Strong link between daily use of marijuana and psychosis

A new study published March 19 in The Lancet Psychiatry medical journal shows a strong link between daily marijuana use and the risk of later psychotic episodes. The study of patients from several European cities found that daily users of marijuana were three times more likely to have a psychotic episode at some point in the future compared to someone who never used the drug. Those who started using cannabis at the age of 15 or younger had a slightly more elevated risk than those who started using in later years.

Those using what researchers called “high potency cannabis” (marijuana with more than 10 percent of tetrahydrocannabinol or THC, the compound responsible for the drug’s psychoactive effects) had higher rates of new cases of psychosis than the other cities in the study. 

Other recent studies show the average potency of marijuana in Europe and the United States in 2017 was 17.1 percent, up from 8.9 percent in 2008. 

Recreational marijuana is now legal in 10 states; medical marijuana is legal in 33. (TAB)