Limited data supports beneficial effects of cannabis for psychiatric conditions, while evidence of harm in psychotic and mood disorders continues to grow, especially among those seeking short-term reward.
Psychiatrists, mental health clinicians, patients with psychiatric conditions considering cannabis, and policymakers.
Limited benefit, growing harm evidence
What the researchers found
The review found increasing documentation of potential harms from cannabis use in patients with psychotic and mood disorders, while data supporting beneficial effects in psychiatric populations remains limited. A reconciled addiction vulnerability and allostatic model was proposed to explain why mentally ill individuals are particularly susceptible to cannabis use disorders.
Why it matters
With cannabis legalization expanding, people with mental illness represent a particularly vulnerable population who may be attracted to cannabis for symptom relief while being at elevated risk for adverse effects.
The numbers in context
The review covers effects across three major psychiatric disorder categories: psychotic disorders (schizophrenia), mood disorders, and anxiety disorders.
How the study worked
Narrative review of cannabis effects across schizophrenia, mood disorders, and anxiety disorders, combined with a theoretical framework integrating addiction vulnerability and allostatic hypotheses.
What this study cannot tell us
Narrative review without systematic methodology. The proposed theoretical framework for understanding co-morbid addiction has not been empirically tested. Evidence base varies in quality across disorder types.
How to read the evidence
Moderate: comprehensive narrative review across multiple disorder types, with a novel theoretical framework.
When this study was published
Published in 2019.
The bigger picture
The tension between cannabis's perceived benefits and documented risks in mental illness reflects a broader challenge in drug policy: how to regulate access while protecting vulnerable populations who may be most drawn to use.
Questions still open
- Can cannabis formulations (e.g., high-CBD, low-THC) be designed to provide psychiatric benefit without the risks associated with high-THC products? How should mental health screening be integrated into cannabis access programs?
Common questions
Is cannabis safe for people with mental illness?
Why are people with mental illness at higher risk from cannabis?
Read the original research
Cannabis and mental illness: a review.
European archives of psychiatry and clinical neuroscience, 269(1), 107-120
Citation
Lowe, Darby J E; Sasiadek, Julia D; Coles, Alexandria S; George, Tony P. (2019). Cannabis and mental illness: a review.. European archives of psychiatry and clinical neuroscience, 269(1), 107-120. https://doi.org/10.1007/s00406-018-0970-7
Explore the wider topic
- LGBTQ+ and Cannabis: Higher Use Rates and Recovery
- Cannabis-Induced Psychosis: What It Is, Who's at Risk, and What to Do
- BetterHelp, Cerebral, and Online Therapy: Honest Review
- Quitting Weed with ADHD: Why It Is Harder and What Actually Helps
- Quitting Weed with Depression: What You Need to Know
- Quitting Weed with PTSD: A Practical Guide
- Self-Medicating with Weed: Why It Works Until It Doesn't
- Weed and OCD: Self-Medicating Intrusive Thoughts
- Weed and PTSD: What the Research Actually Shows
- Weed and Childhood Trauma: ACEs, Self-Medication, and the Path to Real Healing
- Weed and Suicidal Thoughts: What You Need to Know