14 Apr Johns Hopkins Study Finds Cannabis Use May Pose Greater Mental Health Risks in Adolescents than Adults
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Dr. Nicholson
MedicalResearch.com Interview with:
Ryan Nicholson, MD MPH
Anesthesiology Resident, PGY1
Johns Hopkins University School of Medicine
Department of Anesthesiology and Critical Care Medicine
Cannabis use has been increasing steadily in the United States, particularly as legalization expands across states. Alongside this rise, rates of cannabis use disorder (CUD) are growing, along with concern about its potential mental health effects. While previous research has consistently shown that substance use disorders are associated with psychiatric conditions such as depression, anxiety, and psychotic disorders, much less is known about how cannabis use disorder specifically compares to other substance use disorders in terms of psychiatric risk.
A new propensity-matched retrospective cohort analysis from researchers at Johns Hopkins, Brigham and Women’s Hospital, and Tulane University addresses this gap by directly comparing mental health outcomes among patients with CUD versus those with other substance use disorders, while accounting for differences in demographics and clinical characteristics. MedicalResearch.com spoke with lead author Ryan C. Nicholson, MD MPH about the findings.
MedicalResearch.com: What is the background for this study?
Response: Cannabis use has been increasing steadily in the United States, particularly as legalization expands across states. Alongside this rise, we are also seeing increasing rates of cannabis use disorder and growing concern about its potential mental health effects. Maryland, where most of our team is based, had just legalized recreational cannabis prior to the start of this project.
Previous research has consistently shown that substance use disorders are associated with psychiatric conditions such as depression, anxiety, and psychotic disorders. However, most studies compare individuals with SUDs to those without substance use. Much less is known about how cannabis use disorder specifically compares to other substance use disorders in terms of psychiatric risk. Our study aimed to address this gap by directly comparing mental health outcomes among patients with CUD versus those with other SUDs, while accounting for differences in demographics and clinical characteristics.
MedicalResearch.com: What are the main findings?
Response: We found that the relationship between cannabis use disorder and psychiatric outcomes is nuanced and varies significantly by age and comorbidity.
Among adults with CUD only, compared to those with other SUDs, we observed lower risk of schizophrenia, lower risk of major depressive disorder, lower risk of psychotic disorders, and slightly higher risk of anxiety disorders. In contrast, among pediatric patients, the pattern reversed — with higher risk of schizophrenia, higher risk of depression, and higher risk of anxiety disorders.
Additionally, among adults with multiple substance use disorders, those with CUD plus another SUD had lower risks of most psychiatric outcomes compared to individuals with multiple non-cannabis SUDs. Overall, these findings suggest that cannabis-related psychiatric risk is not uniform and depends heavily on age and substance use context.
MedicalResearch.com: Were you surprised by these findings?
Response: Yes, particularly by the differences between adult and pediatric populations. There is a common perception that cannabis is broadly harmful to mental health. While our findings do not contradict that concern, they show that cannabis use disorder is not uniformly associated with higher psychiatric risk compared to other substances, at least among adults. However, the increased risks observed in adolescents are concerning and consistent with existing evidence that the developing brain may be especially vulnerable to cannabis exposure. This divergence by age was one of the most striking aspects of the study.
MedicalResearch.com: How do you explain the higher risk in younger individuals?
Response: There are several possible explanations. First, adolescence is a critical period of brain development, particularly in regions involved in cognition and emotional regulation. The endocannabinoid system, which cannabis directly affects, is highly active during this time, and disruption may have lasting effects.
Second, early cannabis exposure may accelerate or “unmask” underlying vulnerability to psychiatric disorders such as schizophrenia or depression. Finally, it is possible that individuals who are most vulnerable develop psychiatric conditions earlier and therefore are less represented in adult cohorts, creating the appearance of lower risk later in life. These hypotheses are consistent with prior research linking earlier age of cannabis use to increased psychiatric risk.
MedicalResearch.com: How should clinicians interpret these findings?
Response: Clinicians should recognize that all substance use disorders carry psychiatric risk, and that the type of substance and the age of the patient matter significantly. For adolescents, our findings reinforce the importance of screening for cannabis use and counseling about mental health risks.
For adults, cannabis use disorder should still be taken seriously, but clinicians should also consider that other substances — such as opioids or cocaine — may carry equal or greater psychiatric risk in some contexts. Importantly, these results should not be interpreted as cannabis being “safe,” but rather that risk is relative and context-dependent.
MedicalResearch.com: What are the public health or policy implications?
Response: As cannabis becomes more widely available, it is critical to communicate nuanced, evidence-based information. Our findings suggest that prevention efforts should prioritize youth and adolescents, education campaigns should emphasize age-related risks, and policy discussions may consider limits on product potency and improved labeling. A harm-reduction approach may be particularly useful, especially in preventing early initiation of use and associated effects.
MedicalResearch.com: What are the main limitations of the study?
Response: There are several important limitations. We relied on electronic health record data and diagnostic codes, which may not capture all cases. We could not assess dose, frequency, or potency of cannabis use. The study is observational, so we cannot establish causality. Individuals who do not seek care are largely not represented. The database we used — the TriNetX Research Network — has many strengths and tools that empowered us to perform this research; however, there are lingering questions that remain unanswered given some of the notable limitations.
MedicalResearch.com: What future research is needed?
Response: Future studies should aim to better characterize dose-response relationships for cannabis use, examine specific cannabis products and potency levels, explore biological mechanisms including neuroimaging and genetics, and investigate long-term outcomes especially in younger populations. Understanding how cannabis interacts with brain development and psychiatric vulnerability remains a critical area for ongoing research.
Citation
Association of Cannabis Versus Other Substance Use Disorders with Psychiatric Conditions: A Propensity-Matched Retrospective Cohort Analysis
Ryan C. Nicholson, MD MPH1, Una E. Choi, MD2, Ramin Mojtabai, MD PhD3, Johannes Thrul, PhD4,5,6
1Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
2Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Boston, MA
3Department of Psychiatry and Behavioral Sciences, Tulane University School of Medicine, New Orleans, LA
4Department of Mental Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD
5Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD
6Centre for Alcohol Policy Research, La Trobe University, Melbourne, Australia
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Last Updated on April 15, 2026 by Marie Benz MD FAAD