“Psychology Works” Fact Sheet: Cannabis Use

Cannabis is the most commonly used drug in Canada (Canadian Centre of Substance Use and Addiction). and was legalized in 2018. 27% of people reported using cannabis in the past 12 months in 2020 compared to 25% in the previous cycle. In 2020 the % of those who felt daily cannabis use can increase the risk of mental health problems dropped to 66% from 75% in 2019. Usage of cannabis with people aged 16-24 was approximately double that of those 25 years and older.

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_i n_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/m arijuana/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

You can consult with a registered psychologist to find out if psychological interventions might be of help to you. Provincial, territorial and some municipal associations of psychology often maintain referral services. For the names and coordinates of provincial and territorial associations of psychology, go to  https://cpa.ca/public/whatisapsychologist/PTassociations/.

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: Updated by CPA October 2021.

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