As more states legalize marijuana, people are starting to believe it's A-OK to smoke pot on the reg. And it's easy to understand why. If it's legal, it can't be that bad for you, right? Actually, not necessarily. New research shows daily marijuana users, especially those who use high-potency weed, may be three times more likely to develop a psychotic disorder, like schizophrenia, than non-users.

The study, published in The Lancet Psychiatry, looked at 901 people ages 18 to 64 who were first diagnosed with psychosis between 2010 and 2015. (Psychosis is considered to be any disorder that causes a person to lose touch with reality.) The participants were diagnosed at mental health facilities across 11 cities in Europe and Brazil.

The researchers then asked those diagnosed with psychosis as well as a group of more than 1,200 healthy people about their weed habits—things like if they used weed, how often, and what kind. The researchers were then able to identify how much THC (the psychoactive compound in weed) people were getting based on the strains they reported using.

They found the participants who used pot daily were three times more likely to develop psychosis than those who had never used the drug. That number increased to a startling five times more likely for those who used high-potency cannabis—anything with at least 10% THC—daily. In fact, the cities where high-potency weed is most commonly used (London, Paris, and Amsterdam) had the highest rates of new diagnoses of psychosis.

So how common is high-potency weed, anyway? Turns out it's more common than you think. A recent study published in the European Archives of Psychiatry and Clinical Neuroscience found the average potency of weed in Europe and the U.S. in 2017 was 17.1%, nearly double the 8.9% average in 2008.