People who oppose legalizing marijuana just got handed some fuel to add to their anti-Cannabis fire. A study conducted by the University of Oulu in Finland has found that smoking marijuana as an adolescent can lead to psychosis in adulthood.

The study was performed with 6,000 volunteers who started smoking marijuana when they were 15. Their results concluded that even smoke Mary Jane as Little as just five times has an effect on them at age 30.

The release of the results come as Britain has been inundated with campaigners trying to quell the increased amount of Skunk that has flooded the illegal drug market in the U.K.

This isn’t the only study recently that has claimed smoking reefer leads to psychosis. A study from 2017 also made the claim.

Skunk, the potent form of cannabis, is responsible for a quarter of new cases of psychotic mental illness, a study from the University of Montreal released in July reports. Increasing usage from “occasional” to “every day” was found to increase the risk of psychosis by up to 159 percent, according to that study.

Study author Josiane Bourque from the University of Montreal, said: “Our findings confirm that becoming a more regular marijuana user during adolescence is, indeed, associated with a risk of psychotic symptoms. [Psychosis symptoms] may be infrequent and thus not problematic for the adolescent, when these experiences are reported continuously, year after year, then there’s an increased risk of a first psychotic episode or another psychiatric condition.”

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