Cannabis in South Africa
Cannabis in South AfricaReuters

The largest-ever study researching the effect of marijuana use on psychosis has found that people who smoke pot daily are three times more likely to have a psychotic episode compared to people who never smoked pot. The research study was published by the journal The Lancet Psychiatry on Tuesday.

The study, which was supported by foundations in England and Brazil analyzed data from Europe and Brazil from 2010 to 2015, comparing people afflicted with delusions and hallucinations to healthy patients. According to the data, daily marijuana use was more common among patients diagnosed with a first episode of psychosis versus healthy patients.

Psychosis is a term for disruptions to a person's thoughts and emotions leading to an impaired relationship with reality and is usually a symptom of a serious mental disorder.

Those who smoked high-potency weed on a daily basis were five times more likely to experience psychosis than someone who never smoked pot, the study found.

The study showed that in London, Paris and Amsterdam, where the availability and usage of high-potency weed are the highest, the rates of first episodes of psychosis were higher than other cities in the study. According to the study data, roughly half of first episodes of psychosis in Amsterdam were linked to smoking high-potency pot.

Spain, Italy and France, where high-potency pot is not readily available, had the lowest rates of first episodes of psychosis of the cities in the study.

“If you decide to use high-potency marijuana, you should bear in mind: Psychosis is a potential risk,” said Dr. Marta Di Forti, the study's lead author and a psychiatrist and clinician scientist at King's College London.

"There are people across the world who use cannabis for a variety of reasons," Di Forti continued. "Some of them recreationally, some of them for medicinal purposes." They should be aware that using high-potency cannabis comes with a risk."

"They need to know what to look for and ask for help, if they come across characteristics of a psychotic disorder," Di Forti added.