While there’s still much more research needed to form conclusive evidence about the relationship between regular cannabis use (defined as weekly or more frequent cannabis use over a period of months to years) and mental health, many studies have shown a connection. The exact reasons for this connection are not well understood; however, factors including frequency of use, low socio-economic status and personal or family history can contribute to the risk of developing a range of mental health disorders.
Can regular cannabis use cause or exacerbate mental health disorders?
Regardless of other risk factors (such as those mentioned above), regular cannabis use does appear to be associated with a risk of developing a mental health disorder. The level of risk, and the direction of that relationship, can vary from person to person. It also varies across disorders, meaning that depending on the individual, regular cannabis use might carry minimal risk for one disorder but higher risk for another. What’s equally important to note is that most people who consume cannabis do not develop a mental health disorder.
Here’s what we know so far about the relationship between regular cannabis use and mental health disorders.
Schizophrenia and psychosis
Regular cannabis use can increase the risk of developing schizophrenia and/or experiencing psychosis. The risk is strongest for individuals with a family history of schizophrenia and/or psychosis. While further research is required, it’s important to know that even without a family history, regular cannabis use may still increase one’s risk, especially if an individual:
- began use before the age of 16 or 17 (learn more about cannabis and the developing brain)
- consumes cannabis heavily (defined as daily or more frequent use)
- consumes products high in THC
Depression, anxiety and mood disorders
Further research is required to clarify the connection between regular cannabis use and other mental health disorders, such as depression and anxiety disorder. After accounting for other potential risk factors (such as low socio-economic status, alcohol use and genetics), it’s not entirely clear to what extent regular cannabis use may increase one’s risk of developing one of these disorders, though it does appear to be low. It is also important to note that according to the 2023 Medical Cannabis Access Survey, anxiety and depression are two of the most prevalent conditions reported to be managed by Canadians who use cannabis for medical purposes (63.6% and 48.8% respectively), though more research is needed.
Does using cannabis at a young age increase one’s risk of developing a mental health disorder?
Further research is needed to understand possible links between age, cannabis use and mental health disorders. What we know so far is that if cannabis consumption began before the age of 16 or 17, the risk of developing schizophrenia and/or experiencing psychosis as a result of regular cannabis use may be greater. The risk is greatest for those with a family history of schizophrenia and/or psychosis.
What’s the risk of developing a substance use disorder or dependency?
While most people who use cannabis do not become dependent, some people are more prone to developing cannabis use disorder than others because of individual factors such as genetics and pre-existing anxiety, personality and psychiatric disorders.
An estimated 9% of people who consume cannabis will experience cannabis use disorder in their lifetime — but that number jumps to 17% for those who begin consuming cannabis in adolescence (early initiation to cannabis increases one’s risk of developing cannabis use disorder). For those who consume cannabis daily, the risk of developing a cannabis use disorder is between 25% to 50%. (For comparison, the CAMH 2014 Cannabis Policy Framework reported the probability of developing a dependence is about 68% for nicotine, 23% for alcohol and 21% for cocaine.)
If you or someone you know is struggling with mental health or substance use, ConnexOntario provides a 24-hour information service for adults. For support with substance use and addiction, Breaking Free provides Ontarians with free access to digital programming and resources. Good2Talk is a 24-hour support service for post-secondary students ages 17 to 25, and Kids Help Phone is available 24 hours to youth of all ages. Cannabis & Psychosis may also be a helpful resource, as a youth-led, federally-funded project, learn more here. To find mental health and substance use support services in your community, click here.