Summary: New Johns Hopkins research identifies a clear age-dependent association between cannabis use disorder (CUD) and later mental-health diagnoses. Teenagers diagnosed with CUD face substantially higher risks of psychiatric conditions—including schizophrenia, recurrent major depression, and anxiety disorders—than peers with other substance use disorders. In adults, however, CUD was linked with a comparatively lower risk of receiving psychiatric diagnoses versus other substance-using groups, a pattern the authors attribute to possible age-related vulnerability or shifts in when illnesses first appear.
The findings raise important questions about how heavy cannabis exposure interacts with the developing adolescent brain and whether cannabis can hasten the onset of psychiatric disorders in vulnerable young people.
Key Facts & Statistics
- Adolescent vulnerability (age 17 and under):
- 52% higher relative risk of schizophrenia compared with adolescents diagnosed with other substance use disorders.
- 30% higher relative risk of recurrent major depression.
- 21% higher relative risk of anxiety disorders.
- Adult contrast (age 18 and older):
- Adults with CUD showed a 19% lower risk of subsequent schizophrenia (0.34% vs. 0.42%) than adults with other substance use disorders.
- Adults with CUD also had lower relative risks for psychosis, recurrent major depression, and suicide attempts compared with matched adults with noncannabis substance use disorders.
- Large dataset: The analysis used nearly 700,000 U.S. medical records, comparing patients diagnosed with CUD to matched patients diagnosed with other substance use disorders.
- Two leading explanations: 1) An acceleration hypothesis—cannabis exposure in adolescence may trigger an earlier onset of psychiatric illness in those already vulnerable, reducing the apparent risk in older age groups; 2) A self-medication hypothesis—individuals with emerging psychiatric vulnerability may be more likely to use cannabis before formal diagnosis.
Source: Johns Hopkins University
Study overview
This Johns Hopkins–led retrospective cohort study evaluated whether cannabis use disorder presents a unique psychiatric risk compared with other substance use disorders (alcohol, opioids, cocaine, etc.), and whether that risk varies by age. The research team used a large clinical database to identify patients diagnosed with CUD but without prior psychiatric diagnoses and compared them to propensity-matched patients diagnosed with other substance use disorders.
The investigators created two main cohorts: an adult group (age 18 and older; 691,806 patients) and a pediatric group (age 17 and under; 49,586 patients). Matching accounted for demographics and a range of comorbidities and risk factors, enabling comparison of subsequent psychiatric diagnoses, including schizophrenia, psychotic disorders, major depression, bipolar disorder, and anxiety disorders.
Among adolescents, those with CUD had notably higher relative rates of schizophrenia, depression, and anxiety than adolescents diagnosed with other substance use disorders. Among adults, those with CUD—either alone or combined with another SUD—generally had lower rates of later psychiatric diagnoses than matched adults with noncannabis SUDs.
The authors caution that the patterns do not prove causation. Factors such as preexisting biological vulnerability, differences in age of onset, and diagnostic practices could influence the observed associations.
“Is cannabis use a unique risk factor compared to alcohol, opioids, or cocaine? Our results indicate the relative risk depends strongly on age,” says co-author Johannes Thrul, PhD, associate professor in the Department of Mental Health at the Bloomberg School.
The paper appears online in the American Journal of Psychiatry.
Historically, links between cannabis use and psychosis have been observed since early clinical reports in the 20th century. Large longitudinal studies—such as a notable 1987 Swedish conscript study—found a strong association between heavy cannabis use and later schizophrenia. This new U.S.-based database analysis adds to that literature by directly comparing cannabis-related risks with risks associated with other substances across age groups.
Key Questions Answered:
A: In terms of later psychiatric diagnoses, this study suggests yes. Teenagers with CUD had higher relative risks of schizophrenia, recurrent major depression, and anxiety disorders than teenagers diagnosed with other substance use disorders. This does not minimize the well-known physical and social harms of substances like alcohol and opioids, but highlights an elevated psychiatric risk pattern for heavy cannabis use during adolescence.
A: No. The study found lower relative rates of certain psychiatric diagnoses among adults with CUD compared with adults with other substance use disorders, but “lower relative risk” does not equal no risk. Cannabis use can still have negative mental-health and functional consequences for adults, especially with heavy or high-potency products.
A: Not conclusively. The study strengthens the association between adolescent CUD and later schizophrenia but cannot definitively separate causation from alternative explanations. Two plausible interpretations are that heavy cannabis use alters the developing brain or that cannabis use unmasks or accelerates the onset of psychiatric illness in already vulnerable individuals.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The full journal paper was reviewed for accuracy.
- Additional context and explanation were added by the editorial staff where helpful.
About this CUD and psychosis research news
Author: Saznin Mehta
Source: Johns Hopkins University
Contact: Saznin Mehta – Johns Hopkins University
Image: Image credited to Neuroscience News
Original Research: Closed access. “Association of Cannabis Use Disorder Versus Other Substance Use Disorders With Psychiatric Conditions: A Propensity-Matched Retrospective Cohort Analysis” by Ryan C. Nicholson, M.D., M.P.H.; Una E. Choi, M.D.; Ramin Mojtabai, M.D., Ph.D.; and Johannes Thrul, Ph.D. Psychiatry Online
DOI: 10.1176/appi.ajp.2025033
Abstract
Association of Cannabis Use Disorder Versus Other Substance Use Disorders With Psychiatric Conditions: A Propensity-Matched Retrospective Cohort Analysis
Objective:
To compare the subsequent risk of mental disorders among patients diagnosed with cannabis use disorder (CUD) versus those diagnosed with other substance use disorders (SUDs), and to evaluate how these risks differ by age and by comorbid SUDs.
Methods:
Researchers used the TriNetX Research Network to identify patients with SUDs and no prior psychiatric diagnoses. They formed matched cohorts for adults and pediatric patients and performed propensity score matching on demographics and 24 comorbid risk factors. Outcomes measured included subsequent diagnoses of schizophrenia, psychotic disorders, major depression, bipolar disorder, and anxiety disorders.
Results:
In adult cohorts (noncomorbid CUD vs. noncannabis SUDs; N=345,903 each), CUD was associated with lower risks of schizophrenia (0.34% vs. 0.42%; RR=0.81), depression (1.35% vs. 1.74%; RR=0.78), and psychotic disorders (0.36% vs. 0.52%; RR=0.68). In pediatric cohorts (CUD vs. noncannabis SUDs; N=24,793 each), CUD was associated with higher risks of schizophrenia (0.29% vs. 0.19%; RR=1.52), depression (1.65% vs. 1.27%; RR=1.30), and anxiety disorders (8.13% vs. 6.71%; RR=1.21). Adults with CUD plus another SUD also showed lower relative risks for several psychiatric outcomes compared with adults with noncannabis comorbid SUDs.
Conclusions:
Risks of subsequent mental disorders associated with cannabis use disorder vary by age and by the presence of other substance use disorders. The pattern could reflect an earlier onset of psychiatric disorders among adolescent cannabis users or age-related differences in how CUD affects mental health. Further longitudinal and mechanistic studies are needed to clarify causation and to guide prevention and clinical practice.