Teenagers who smoke cannabis at least once a week are less likely to finish school, enrol in university or obtain a degree, according to UNSW research that challenges notions that the drug is less harmful than alcohol.
A study of 3,600 young people from Australia and New Zealand found lower educational outcomes for those who smoked cannabis before the age of 17.
Just under half (47%) of those who used the drug at least weekly failed to complete high school, 69% did not enrol in university and 88% did not obtain a degree, according to the study which was led by UNSW’s National Drug and Alcohol Research Centre (NDARC).
These teenagers had odds of not progressing with formal education that were between 1.6 to 2 times higher than cannabis non-users.
“I often hear the claim that cannabis is less harmful than alcohol, but when you look specifically at education outcomes this doesn’t hold up.”
The magnitude of the effect of cannabis use on educational attainment remained significant even after taking into account 53 individual, parental and peer factors which might otherwise explain the association.
In contrast, after taking these factors into account the study found there was no independent association between early alcohol use and educational attainment.
NDARC Senior Research Fellow, Dr Edmund Silins, said the finding that cannabis use made a larger contribution to not progressing with education compared to alcohol use was relevant to the debate about the relative harms of these drugs.
“I often hear the claim that cannabis is less harmful than alcohol, but when you look specifically at education outcomes this doesn’t hold up,” Dr Silins said.
Study findings strengthen the case for cannabis’ adverse effects on adolescent development.
Dr Silins said the more frequent the use of cannabis, the stronger the association was with non-progression with formal education.
“There’s a need for more targeted prevention work in young people particularly as finishing high school and getting a degree are such important milestones.”
The study did not examine how cannabis use in young and frequent users leads to poor educational attainment, but Dr Silins said other research has shown that heavy cannabis use can affect brain development and function.
“Alternatively, early cannabis use might be a marker of developmental trajectories that put young people at increased risk of not completing school,” Dr Silins said.
Supported by NHMRC funding, the study was co-authored by investigators from the University of Otago, the University of Queensland, the University of Melbourne, and Deakin University. NDARC is supported by funding from the Australian Government.
The study has been published in the journal Drug and Alcohol Dependence.