Adolescent Cannabis Use Linked To Young Adult Adverse Outcomes Interview with:
Edmund Silins PhD, Research Fellow
National Drug and Alcohol Research Centre
UNSW Medicine University of New South Wales
Sydney  Australia

Medical Research: What are the main findings of the study?

Dr. Silins: There were three particularly interesting aspects to the findings.

  • Firstly, we found clear and consistent associations between adolescent cannabis use and the young adult outcomes investigated.
  • Secondly, there was evidence of a dose-response effect such that the more frequently adolescents used cannabis the more likely they were to experience harms later in life.
  • Thirdly, for most outcomes, these associations remained even after taking into account a wide range of other factors which might potentially explain them.

The adverse effects were greatest for daily cannabis users. Specifically, adolescents who were daily cannabis users were, by the age of 25, more than 60% less likely to complete high school or obtain a university degree, seven times more likely to have attempted suicide, 18 times more likely to have been cannabis dependent, and eight times more likely to have used other illicit drugs, than adolescents who had never used the drug.

Medical Research: Were any of the findings unexpected?

Dr. Silins: We were surprised to find that for most outcomes the associations persisted even after taking into account 53 individual, parental, and peer-level factors which may potentially explain them. The findings provide strong evidence of a more direct link between adolescent cannabis use and young adult wellbeing, mental health, and achievement.

Medical Research: What should clinicians and patients take away from your report?

Dr. Silins: The findings suggest that the prevention or delay of regular cannabis use in adolescents will have broad health and social benefits. As young people typically do not present to clinical services for management of cannabis use, screening for cannabis use in those under the age of 16 should be routine for GPs, paediatricians, child and adolescent psychiatrists, primary care nurses and school counsellors.

It is important to encourage adolescents not to use cannabis, or at the very least, delay their use. This is a particularly important message because the developing adolescent brain is very susceptible to the harmful effects of cannabis use.

Parents also have an important part in preventing or delaying their child’s cannabis use. One of the most important things a parent can do is develop good communication with their child and have conversations about cannabis which are open, honest and non-judgemental. If their teenager is already using cannabis, it’s important to raise the issue even though confronting them about their use will probably be difficult. Be open and non-judgemental, offer support, and be prepared to have ongoing conversations about cannabis. If all else fails, professional help can be sought through a general practitioner or counsellor.


Young adult sequelae of adolescent cannabis use: an integrative analysis
Dr Edmund Silins PhD,L John Horwood MSc,Prof George C Patton MD,Prof David M Fergusson PhD,Craig A Olsson PhD,Delyse M Hutchinson PhD,Elizabeth Spry BA,Prof John W Toumbourou PhD,Prof Louisa Degenhardt PhD,Wendy Swift PhD,Carolyn Coffey PhD,Robert J Tait PhD,Primrose Letcher PhD,Prof Jan Copeland PhD,Richard P Mattick PhD,for the Cannabis Cohorts Research Consortium
The Lancet Psychiatry – 1 September 2014 ( Vol. 1, Issue 4, Pages 286-293 )
DOI: 10.1016/S2215-0366(14)70307-4


Last Updated on September 10, 2014 by Marie Benz MD FAAD