Cannabis and teen link worries

Cannabis use during adolescence is linked to an increased risk of depression and suicidal behaviour in young adulthood, a new study has found.

But the level of increased risk of depression and suicidal thoughts and attempts found in United States study is only low to moderate. No link was found to anxiety.

The research combines the results of 11 separate studies published over the past 15 years that together included more than 23,000 adolescent cannabis smokers and assessed their mental health when aged 18 to 32. People with prior depression were excluded.

“This review both confirms and reinforces findings from the research literature on the adverse psychological effects of regular cannabis use by mid- to late adolescents,” said Dr Joe Boden, the deputy director of the University of Otago’s Christchurch long-term health and development study.

“The findings of this [US] study further reinforce our concerns about the public health implications of any changes we may choose to make to cannabis laws in New Zealand,” Boden told the Science Media Centre.

The Government announced in December it will change the law to treat use of all illegal drugs as a health matter — and crack down harder on the suppliers of synthetic drugs.

The new study, published in the Journal of the American Medical Association, does not state how much cannabis the research participants smoked, which is considered a significant omission.

And the study type could not show causal links.