Does Cannabis Cause Schizophrenia? 

Liz Filmer
15 Jun 2022

A study has claimed that teens who occasionally use cannabis are just as likely to develop schizophrenia as daily smokers. 

Experts have cautioned teenagers to evade using cannabis while their brains are still maturing. Researchers reviewed more than 590 papers on cannabis use in  12-18-year-olds compared to non-smokers. Results revealed that smoking the drug in low amounts induced the exact six-fold increased risk of getting schizophrenia as doing it daily. 

NHS figures show cannabis use in 16 to 24-year-olds is rising in England and Wales. 32.6 per cent admitted using it in 2020, compared to 30.2 per cent in 2016. Additional data revealed psychiatric hospital admission among cannabis users has skyrocketed by 74 per cent since the Scottish Government virtually decriminalised the drug.

Scottish police revised its recommendations in January 2016. Anyone found possessing cannabis could now be issued a warning rather than risking prosecution. The number of prosecutions fell dramatically. However, in 2021, a record 1,263 Scottish patients sought NHS treatment for psychiatric conditions.

The review included 591 studies between 2010 and 2020 about cannabis use in teenagers worldwide. Cannabis users were classified into two groups: low-frequency users — who smoke twice a week or less — and higher-frequency users — who smoke every day. 

They compared the groups' probabilities of developing schizophrenia to teenagers who had never smoked the drug. The researchers found that the mental disorder's chances were six times higher in both groups. 

It comes following a heap of research that further strengthens the link between cannabis and cognitive disorders such as schizophrenia. One US study recorded that weed-associated psychosis admissions were almost three times higher in states where cannabis has been legalised.  

Despite numerous studies linking cannabis and schizophrenia, scientists do not yet fully understand how the plant may increase your risk of developing the issue.

It's not all bad news, though. Other research has indicated that cannabis may not be enough to induce extreme mental conditions. A Harvard study from 2014 on cannabis users with and without a genetic predisposition for schizophrenia advised that cannabis use alone does not increase the risk of developing the disorder. In this study, the disorder's risk was found to be higher in those with a family history, regardless of cannabis use. 

Liz Filmer