As many as 60,000 cases of depression in adults could have been avoided by preventing teenagers trying cannabis, researchers behind a major new analysis have said.

‘Some teenagers think because it’s a plant it’s without harm – it’s important to inform adolescents about the risks and the kind of cannabis they use.’

In the largest study to date, researchers from Canada, the USA and Oxford University found robust evidence that trying the drug before the age of 18 meant young people were 37% more likely to develop depression and suicidal thoughts in early adulthood than teenagers who didn’t.

The study, published in JAMA Psychiatry on 13th February 2019, is a meta-analysis of 11 other studies following 23,000 people in all, tracing their drug use and mental health from the point before they had tried cannabis for the first time up until the age of 34.