The relationship between cannabis (marijuana) use and psychiatric disorders is complex, and more research is needed to better understand the short- and long-term impacts of cannabis use on mental health. Considerable—though not all—evidence has linked cannabis use to earlier onset of psychosis in people with genetic risk factors for psychotic disorders, including schizophrenia, as well as worse symptoms in people who already have these conditions. Although less consistent, there is also evidence linking cannabis use to other mental illnesses and self-harm, including suicidal thoughts and behaviors.
While people with mental illnesses and related symptoms are more likely to use cannabis,121 more research is needed to better understand how mental illness symptoms relate to cannabis use. Many factors—such as the amount of drug consumed, the frequency of use, the potency (THC content) of and type of cannabis product, and a person’s age at first use—have been shown to influence the relationship between cannabis use and mental health.122, 123 Similarly, many factors that influence mental health—such as genes, trauma, and stress—also influence how likely someone is to use drugs, including cannabis. Given these related genetic and environmental vulnerabilities, additional data from prospective, longitudinal research (studies that measure participants’ health over long periods of time) are needed to determine whether, to what extent, and for whom cannabis may cause or contribute to poor mental health outcomes.
Research has shown that cannabis use is associated with an increased risk for an earlier onset of psychotic disorders (such as schizophrenia) in people with other risk factors, such as family history.122,123,138 Cannabis intoxication can also induce a temporary psychotic episode in some individuals, especially at high doses. Experiencing such an episode may be linked with a risk for later developing a psychotic disorder.125-127 A person’s genetics may play a role in this relationship.61,128-131
The relationship between cannabis use and other mental illnesses is less clear. Some research has shown an increased risk of depression in those who use cannabis during adolescence.132-133 More robustly, research has linked cannabis use with suicidal thoughts and behaviors among teens 65-66,134-135 and military veterans in the United States.136-137
This page was updated in May, 2023. This publication as a whole was last updated in 2020.