I’ve seen the enormous harm this drug can do – legalisation is far too great a risk to take

Cannabis can be both addictive and harmful. Our understanding of the precise extent of the health implications of cannabis use is developing but, as this new systematic review of more than 23,000 individuals from across 11 international studies shows, there is much to be concerned about.

The alarm bells have been ringing for a while, even if some have preferred not to listen to them. On the eve of the first legal retail sales of recreational cannabis in Canada, the Canadian Medical Association Journal published an editorial which referred to legalisation as “a national, uncontrolled experiment in which the profits of cannabis producers and tax revenues are squarely pitched against the health of Canadians”.

That’s not just an opinion – there is a compelling body of evidence, spanning 20 years and multiple jurisdictions, of a dangerous relationship between cannabis use, psychosis, and diminished brain function, particularly among frequent and younger users.

Despite the many cheerleaders for legalisation, many with a great deal of experience in and concern for public health, strongly oppose it. And I’ve seen why first hand.

When I co-founded the charity Twentytwenty, its focus was on supporting disadvantaged 16–21- yearolds who were not in education, employment or training. It was a difficult job. But when those kids turned up stoned, it was an impossible job. At Twentytwenty we lived a reality which meant every single day we saw the enormous harm that cannabis could do.

Research carried out by the Centre for Social Justice last year showed that legalisation would mean more than a million new users under 25, a sharp uptick in frequency among existing users, and hundreds of thousands gripped by addiction.

Legalising cannabis is far too great a risk to take.

Andy Cook is chief executive of the Centre for Social Justice

By Andy Cook