Cannabis in Psychiatry

The Role of Cannabis in Psychiatry: A Review of Evidence from Peer-Reviewed Studies

Cannabis has long been a subject of debate in both medical and social circles, with its use varying from strictly recreational to more therapeutic purposes. Over the past few decades, there has been a growing interest in the potential medicinal value, particularly in the field of psychiatry. While cannabis has indeed shown promise in treating certain psychiatric conditions, it also carries risks that warrant careful examination. In this blog post, we will explore the role of cannabis in psychiatry, reviewing only high-quality peer-reviewed studies to better understand its potential benefits and drawbacks.

Cannabis and Psychiatric Disorders: A Complex Relationship

The plant cannabis contains over 100 active compounds known as cannabinoids, with tetrahydrocannabinol (THC) and cannabidiol (CBD) being the most studied. THC is the psychoactive compound responsible for the “high” associated with cannabis, while CBD has been linked to a calmer and relaxation feeling, with both anxiolytic and antipsychotic effects. The interaction between these compounds and the endocannabinoid system—the body’s natural system involved in regulating mood, memory, and stress—speaks to the influence that cannabis may have over various psychiatric conditions and symptoms. However, the relationship between cannabis and mental health is not straightforward. The primary and most notable considerations being the effect of cannabis use on mood, psychosis, cognitive function or memory, and on traumatic stress symptoms. 

Cannabis for Anxiety and Depression

Several studies have investigated the use of cannabis for the treatment of anxiety and depression, two of the most prevalent mental health conditions globally. In a 2020 meta-analysis published in JAMA Psychiatry, researchers reviewed the effectiveness of cannabinoids in treating anxiety and found moderate evidence supporting the anxiolytic effects of CBD. Specifically, CBD was shown to reduce anxiety levels in individuals with social anxiety disorder and generalized anxiety disorder (GAD). However, the evidence was mixed, with some studies suggesting that THC, especially in higher doses, could exacerbate anxiety.

For depression, the results are similarly complex. In a 2021 study published in Frontiers in Psychiatry, authors found that CBD could potentially have antidepressant-like effects, particularly in animal models, by interacting with serotonin receptors. However, the clinical evidence for CBD as a treatment for depression remains limited, and more rigorous human trials are needed. THC, on the other hand, has been shown to have a mood-elevating effect, but chronic use can lead to physical dependence and worsen mood disorders, as highlighted in a 2019 study in The Lancet Psychiatry. These findings underscore the importance of dosage and the specific cannabinoid profile when considering cannabis as a treatment for anxiety or depression, as there can be quite a variety available. 

Cannabis and Psychosis

One of the most concerning aspects of cannabis use in psychiatry is its association with psychotic symptoms, including those that can meet the criteria for schizophrenia. A growing body of research suggests that cannabis, especially strains high in THC and lower in CBD, can trigger or exacerbate psychotic symptoms. This particularly occurs in individuals who are genetically predisposed to psychotic disorders. In a 2016 study published in The Lancet Psychiatry, authors found that regular cannabis use was associated with a significantly increased risk of psychosis, with the risk being higher among those who used high-potency cannabis or began using cannabis at an early age.

Conversely, there is emerging evidence that CBD may have antipsychotic properties, thereby mitigating the risk from THC consumption. In a 2018 study in The American Journal of Psychiatry, researchers found that CBD could reduce psychotic symptoms in patients with schizophrenia. These findings suggest that while THC may be harmful to individuals at risk for psychosis, CBD may protect against some of these risks.

Cannabis Use and Cognitive Function

Cannabis use, especially heavy and long-term use, has been shown to impact cognitive function, particularly in areas related to memory, learning, and executive function. In a 2018 study published in JAMA Network Open, authors found that long-term cannabis use was associated with impaired memory and attention in both adolescents and adults. Moreover, in a 2020 systematic review in Psychological Medicine, reviewers reported that cannabis use in adolescents could lead to persistent cognitive deficits, with drops in IQ scores and  more pronounced effects in individuals who begin using cannabis before the age of 18.

On the other hand, in a 2020 study in Cannabis and Cannabinoid Research, authors suggested that CBD might protect against cannabis-induced cognitive deficits, though further studies are needed to confirm these findings. This further highlights the complexities of  the relationship between cannabinoids and cognitive function.

Cannabis and Post-Traumatic Stress Disorder (PTSD)

Post-traumatic stress disorder (PTSD) is another psychiatric condition where cannabis has been studied for its potential therapeutic effects. In a 2017 systematic review published in JAMA, authors concluded that there was moderate evidence supporting the use of cannabinoids in alleviating PTSD symptoms. Both THC and CBD were found to reduce symptoms such as hyperarousal and intrusive memories, although THC use also carried the risk of exacerbating symptoms in some individuals. In a more recent 2020 clinical trial published in Frontiers in Public Health, researchers found that CBD could reduce anxiety and improve sleep in individuals with PTSD, suggesting that CBD may be a safer alternative to THC for this condition. Cannabis has also been found to reduce nightmares in some patients.

The Risks and Limitations of Cannabis in Psychiatry

When considered altogether, the use of cannabis in psychiatry is confusing. While cannabis may offer therapeutic potential for various psychiatric conditions, it is essential to acknowledge the risks and limitations associated with its use. High-THC cannabis, in particular, can lead to adverse mental health effects, including increased risk of anxiety, paranoia, and psychosis. Rarely are psychiatric providers well versed or confident in navigating cannabis use. 

Moreover, the lack of standardized dosages and inconsistent formulations in cannabis products complicate the application of cannabis to clinical psychiatry and make it very difficult for individuals to identify what products might be right for them. Having a helpful and knowledgeable provider will be essential in ensuring safe use- especially if you are also taking other medications and/or supplements. 

Finally, studies may be minimally helpful and may be influenced by society views. Many studies on cannabis and psychiatry have relied on self-reported data, which can introduce biases and inaccuracies. The field is still in its early stages, and more large-scale, randomized controlled trials (RCTs) are needed to establish definitive clinical guidelines for the use of cannabis in psychiatric treatment. For now, you need a provider who works with you to achieve your goals of care.

Conclusion

Cannabis holds promise as a treatment for certain psychiatric conditions, particularly anxiety, mood, PTSD, and even psychotic disorders. Cannabinoids such as CBD have shown therapeutic potential without the adverse effects associated with THC, making them a viable alternative in some cases. However, the risks associated with cannabis use—especially concerning THC and psychosis—

cannot be ignored. Healthcare providers must exercise consideration when recommending cannabis as a treatment option, carefully considering the individual patient's condition, age, and potential risks. An integrative, or wholistic, psychiatric provider considering all aspects of each patient can offer solutions here. In our practice, assisting with safe cannabis consumption to meet curated psychiatric treatment goals may provide an option for successfully navigating cannabis in psychiatry.

References

• JAMA Psychiatry (2020). "Cannabinoids for Anxiety Disorders: A Systematic Review and Meta-Analysis."

• Frontiers in Psychiatry (2021). "Cannabidiol as an Antidepressant: Preclinical and Clinical Evidence."

• The Lancet Psychiatry (2019). "Cannabis Use and Its Association with Mood Disorders."

• The American Journal of Psychiatry (2018). "Antipsychotic Effects of Cannabidiol in Schizophrenia: A Systematic Review."

• JAMA Network Open (2018). "Impact of Long-Term Cannabis Use on Cognitive Function."

• Psychological Medicine (2020). "Long-Term Cannabis Use and Cognitive Decline."

• Cannabis and Cannabinoid Research (2020). "Cannabidiol and Its Effects on Cannabis-Induced Cognitive Deficits."

• JAMA (2017). "Cannabinoids for Post-Traumatic Stress Disorder: A Systematic Review."

• Frontiers in Public Health (2020). "Cannabidiol and Post-Traumatic Stress Disorder: Evidence from Clinical Trials."

• More available upon request