Legalization of cannabis for medical and recreational use made it increasingly available worldwide. A new research in Europe associates the daily use of cannabis to increased risks of psychotic disorder.

The study published in the Lancet Psychiatry Journal probed the patterns of cannabis or marijuana use across Europe to show its impact on mental health, particularly on the incidence of psychotic disorder.

Symptoms of this mental health disorder include psychosis or having delusions and hallucinations.

Users More At Risk

The research revealed that people who use weed every day are three times more likely to develop first-episode psychosis compared to non-users. The risk increases to five times for people who use high-potency cannabis on a daily basis.

Frequency and potency of marijuana use are the guiding factors in determining the odds of developing psychosis.

"The more cannabis you consume the more likely you are to develop a psychotic disorder," said Dr. Marta Di Forti, lead author of the study.

Marijuana And Psychosis

The research involved 901 patients aged 18 to 64 who have first-episode psychosis and have used mental health services in major sites across Europe between 2010 to 2015. The study covered the United Kingdom, the Netherlands, France, Spain, Italy, and Brazil.

Scientists from the Institute of Psychiatry, Psychology and Neuroscience at King's College London compared the assessment results of psychosis patients with that of 1,237 matched non-patients recruited for the study.

Participants were made to answer a questionnaire to know if they used cannabis in their lifetime; if the answer was affirmative, they were requested to give details on their pattern of use.

Di Forti and her team also identified and categorized the low potency and high potency tetrahydrocannabinol or THC — the psychoactive component of cannabis. High potency strains are those with THC concentration above 10 percent.

Overall, cannabis use was found to be more common among patients experiencing psychosis.

The study suggests that at least 12 percent of new cases of first-episode psychosis may be linked to high-potent marijuana use. The link was strongest in London with 30.3 percent of new cases and in Amsterdam with half of the new cases. High potent weed strains are commonly available in both countries.

Although inconclusive, the study has significant implications for mental health services and public health. The public needs information about the mental health hazards of daily use of high-potency cannabis.

"The risks are increased when the drug is high in potency, used by children and young people and when taken frequently," said Dr. Adrian James of Royal College of Psychiatrists in the UK.

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