Substance Use
& Psychosis
In recent years, cannabis has become more widely accessible for both medical and recreational use, prompting growing concern among researchers, clinicians, and health providers. Increased attention is now being directed toward the association between cannabis use and psychosis. Although public perception sometimes views cannabis as safe or therapeutic, emerging scientific evidence suggests a more nuanced and potentially concerning reality.
Cannabis use, especially in adolescents and individuals with underlying mental health vulnerabilities, is increasingly linked to psychotic symptoms and psychiatric disorders. According to the 2021 National Survey on Drug Use and Health in the U.S., over 52 million individuals aged 12 and older used cannabis, with 16.3 million meeting criteria for Cannabis Use Disorder (CUD). This has sparked growing concern among clinicians and researchers about the psychiatric implications of heavy and frequent cannabis use.
While not all teens who use cannabis will suffer adverse outcomes, a subset experiences profound and long-lasting effects, especially with the widespread availability of high-THC products. Research increasingly shows that adolescent cannabis use can lead to structural and functional brain changes that can contribute to experiencing adverse behavioral and mental health outcomes.
The prevalence of cannabis use in patients with psychosis is high. Cannabis use is highly prevalent among individuals with psychosis, with approximately 36% of patients experiencing first-episode psychosis and 21% of those with established schizophrenia meeting the diagnostic criteria for cannabis use disorder. Additionally, the harms associated with cannabis use in these populations appear to be increasing.
Cannabis use and CUD are increasingly linked to mental health conditions such as anxiety, depression, PTSD, schizophrenia, bipolar disorder, and ADHD. Adolescents are especially at risk, as they begin using earlier and encounter more potent products in a low-stigma, high-access environment—raising the likelihood of lasting psychiatric effects, including a strong association with schizophrenia.
Comparisons with other substances such as alcohol and amphetamines offer a valuable perspective. Alcohol-related psychosis (ARP), though less commonly discussed, is an established psychiatric complication. Data shows that ARP can precede chronic conditions like schizophrenia, with a conversion risk of 22%, second only to cannabis-induced psychosis.
Similarly, amphetamine-induced psychosis, which often presents with delusions and hallucinations, mimics acute schizophrenia. As with cannabis, the risk of psychosis increases with higher dosages and daily use. Amphetamine use is rising in North America and is associated with a growing number of overdose deaths.
Together, these findings underscore the need for updated public health messaging, clinical education, and policy reform. While cannabis is increasingly normalized, its association with serious psychiatric outcomes, particularly among youth, demands careful attention.
Early intervention is critical in the treatment and recovery process for individuals experiencing substance use and psychosis. Achieving abstinence from substances as early as possible significantly enhances the effectiveness of treatment. If abstinence is not possible, a significant reduction in use is critical. In many cases, once an individual discontinues substance use and withdrawal symptoms subside, psychotic symptoms also resolve.
However, in approximately 25% of cases, psychotic symptoms may persist, leading to a potential diagnosis within the schizophrenia spectrum.
Close monitoring by a physician or advanced practice provider during the withdrawal phase is essential to ensure safety and support stabilization. Comprehensive treatment typically includes a combination of psychotherapy and pharmacologic interventions, particularly the use of antipsychotic medications, to address both substance use and psychosis effectively.
As cannabis use increases, especially among adolescents, it’s important to challenge assumptions about its safety. Growing evidence links high-potency, early, and chronic use to various psychiatric disorders, indicating that cannabis is not a low-risk substance.
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