“Psychology Works” Fact Sheet: Cannabis Use

Cannabis is the most commonly used illegal drug in Canada (Canadian Centre of Substance Use and Addiction). In April 2017, the Government of Canada took steps to legalize cannabis for recreational purposes. It is currently legally available for medical purposes.

How does Cannabis affect young people?

Research suggests that regular or heavy use of cannabis in adolescence (ages 10-20 according to the World Health Organization) is related to difficulty in school, lower income, suicidality, greater welfare dependence and unemployment, as well as lower life satisfaction.

Our brains continue to develop up to the age of 24 years. Cannabis can change the way the brain develops, and medical imaging tests have shown differences between brains of cannabis users and non-cannabis users. Specifically, verbal learning, memory, and attention are negatively affected by acute and chronic use of cannabis. This effect can last even after someone stops using cannabis.

How does Cannabis affect mental health?

Cannabis use is related to mental health and mental illness. For example, research suggests that cannabis use is associated with psychosis, especially for those who use at an earlier age, who frequently use high potency cannabis, and who have a genetic predisposition for psychosis. There is also some research suggesting that cannabis use is associated with depression, bipolar disorder, and anxiety, though causality has not yet been clearly established for all such outcomes.

How does Cannabis affect judgement and decision making?

Executive functioning, which is our ability to plan, prioritize, and problem solve, is negatively affected by heavy or chronic cannabis use. This can lead to poor decision-making, planning, and organizing. Acute cannabis use is associated with an increased risk of motor vehicle collisions, especially fatal collisions.

What are the prevention and treatment options for dependence and abuse of Cannabis?

Research suggests that structured, school-based programs focused on making wise decisions about cannabis use, healthy coping, and substance use resistance skills offered in early adolescence can have strong effects on reducing cannabis use. Motivational Enhancement Therapy (MET) helps individuals resolve their ambivalence to get treatment and stop their drug use, and it has shown positive effects on reducing cannabis use in youth. Cognitive-behavioural therapy, motivational interviewing, and multi-dimensional family therapy are also shown to be helpful.

Where can I get more information?

Recommendations for the Legalization of Cannabis in Canada – provides further information regarding the research and recommendations for the legalization of cannabis in Canada: http://cpa.ca/docs/File/Position/Position_Paper_Recommendations_for_the_Legalization_of_Cannabis_in_Canada-September_2017.pdf

The Centre for Addiction and Mental Health – provides information about use and abuse of cannabis: http://www.camh.ca/en/hospital/health_information/a_z_mental_health_and_addiction_information/marijuana/Pages/about_marijuana.aspx

Government of Canada – general information about cannabis: https://www.canada.ca/en/health-canada/services/substance-abuse/controlled-illegal-drugs/about-marijuana.html

Here to Help – Cannabis Use and Youth: A parents’ guide: http://www.heretohelp.bc.ca/workbook/cannabis-use-and-youth-a-parents-guide

This fact sheet has been prepared for the Canadian Psychological Association (CPA) with information from the Recommendations for the Legalization Cannabis in Canada, a position paper prepared for the CPA by its Task Force on the Legalization of Cannabis.

Date: January 9, 2018

Your opinion matters! Please contact us with questions or comments about any of the Psychology Works Fact Sheets by sending an email to:  factsheets@cpa.ca

Canadian Psychological Association
141 Laurier Avenue West, Suite 702
Ottawa, Ontario    K1P 5J3
Tel:  613-237-2144
Toll free (in Canada):  1-888-472-0657