Cannabis Use and Psychiatric Disorders: What the Research Shows About Dual Diagnoses
Cannabis use is consistently associated with psychosis and progression to other drugs, with adolescent-onset use carrying the strongest psychiatric risks.
Quick Facts
What This Study Found
This narrative review examined the relationship between cannabis use and psychiatric disorders across multiple categories. The strongest evidence linked cannabis use to psychosis and to subsequent use of other illicit substances.
The association between cannabis and bipolar disorder appeared in a few reports but remained less established. For depression and anxiety, the evidence was mixed, with some studies finding associations and others not.
Age of cannabis use emerged as a critical factor. Adolescent-onset cannabis use showed the strongest associations with later psychiatric disorders, compared to adult-onset use. The reviewers noted that most studies struggled to account for confounding factors like withdrawal symptoms, other substance use, and childhood experiences.
Key Numbers
The review did not report pooled statistics but synthesized findings across multiple studies, concluding that "substantial evidence" supports cannabis-psychosis and cannabis-gateway associations, while depression and anxiety links remain "mixed."
How They Did This
The researchers conducted a narrative review using PubMed and PsychInfo databases, searching for literature on cannabis and psychiatric comorbidity using keywords related to cannabis, psychosis, schizophrenia, mood disorders, depression, mania, bipolar disorder, and anxiety.
Why This Research Matters
As cannabis legalization expands, understanding the psychiatric risks associated with use becomes increasingly important. This review consolidates evidence showing that the relationship between cannabis and mental health is consistently adverse when associations exist, which has implications for clinical screening and public health messaging.
The Bigger Picture
This review sits within a growing body of literature highlighting adolescence as a particularly vulnerable window for cannabis-related psychiatric risk. The consistent finding that younger users face greater risk supports age-restricted access policies and targeted prevention efforts for adolescents.
What This Study Doesn't Tell Us
As a narrative rather than systematic review, this study did not use standardized methods for study selection or quality assessment. Many of the reviewed studies did not adequately control for confounding factors including other substance use, withdrawal effects, or pre-existing psychiatric conditions.
Questions This Raises
- ?Does the type or potency of cannabis used influence psychiatric risk differently?
- ?Are there genetic factors that make certain adolescents more vulnerable to cannabis-related psychiatric outcomes?
- ?Would better-controlled studies change the mixed findings on cannabis-depression links?
Trust & Context
- Key Stat:
- Adolescent-onset cannabis use showed the strongest associations with later psychiatric disorders
- Evidence Grade:
- Narrative review synthesizing multiple studies; moderate because it consolidates substantial evidence but lacks systematic methodology.
- Study Age:
- Published in 2017, this review covers literature available through 2016.
- Original Title:
- Cannabis and development of dual diagnoses: A literature review.
- Published In:
- The American journal of drug and alcohol abuse, 43(4), 442-455 (2017)
- Authors:
- Hanna, Rebecca C, Perez, Jessica M, Ghose, Subroto(2)
- Database ID:
- RTHC-01394
Evidence Hierarchy
Summarizes existing research without a strict systematic method.
What do these levels mean? →Frequently Asked Questions
Does cannabis cause psychosis?
This review found substantial evidence of an association between cannabis use and psychosis, though establishing direct causation requires accounting for many confounding factors. The association is strongest for adolescent-onset use.
Is cannabis a gateway drug?
The review found substantial evidence that cannabis use is associated with subsequent use of other illicit substances, though the mechanisms behind this association (social, biological, or both) remain debated.
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Cite This Study
https://rethinkthc.com/research/RTHC-01394APA
Hanna, Rebecca C; Perez, Jessica M; Ghose, Subroto. (2017). Cannabis and development of dual diagnoses: A literature review.. The American journal of drug and alcohol abuse, 43(4), 442-455. https://doi.org/10.1080/00952990.2016.1213273
MLA
Hanna, Rebecca C, et al. "Cannabis and development of dual diagnoses: A literature review.." The American journal of drug and alcohol abuse, 2017. https://doi.org/10.1080/00952990.2016.1213273
RethinkTHC
RethinkTHC Research Database. "Cannabis and development of dual diagnoses: A literature rev..." RTHC-01394. Retrieved from https://rethinkthc.com/research/hanna-2017-cannabis-and-development-of
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.