Genetic overlap between cannabis use and psychotic disorders suggests shared biological roots
A Lancet Psychiatry study found shared genetic architecture between cannabis use and schizophrenia/bipolar disorder, with causal evidence running in both directions.
Quick Facts
What This Study Found
Genome-wide genetic correlations between psychotic disorders and cannabis phenotypes ranged from 0.22-0.35. Causal analysis showed psychotic disorders had a causal effect on cannabis phenotypes, and lifetime cannabis use had a causal effect on bipolar disorder. Polygenic scores for cannabis predicted psychotic disorders independently. Shared loci implicated neuronal cells and drug-gene targets for nicotine, alcohol, and duloxetine.
Key Numbers
Genetic correlations 0.22-0.35; 3-27 shared loci per phenotype pair; 2,181 participants in polygenic score analyses (400 bipolar, 697 schizophrenia, 1,044 controls); 48.6% female; mean age 33.1 years
How They Did This
Genome-wide association summary statistics from European ancestry (Psychiatric Genomics Consortium, UK Biobank, International Cannabis Consortium). Included heritability estimation, genetic correlations, shared loci identification, causal analyses, and polygenic risk score analyses using the Norwegian Thematically Organized Psychosis cohort (n=2,181).
Why This Research Matters
Published in Lancet Psychiatry, this study provides the most comprehensive genetic evidence to date that the cannabis-psychosis relationship involves shared biological vulnerability, not just one causing the other.
The Bigger Picture
The bidirectional causal findings suggest that some individuals are genetically predisposed to both cannabis use and psychotic disorders, supporting targeted prevention in those with high genetic risk rather than population-wide approaches.
What This Study Doesn't Tell Us
Limited to European ancestry populations. Mendelian randomization assumptions may not fully hold. Cannot identify specific causal mechanisms. Shared GWAS loci do not necessarily mean shared functional pathways.
Questions This Raises
- ?Could genetic risk scores be used clinically to identify individuals who should avoid cannabis?
- ?Do the shared loci suggest novel treatment targets for both conditions?
Trust & Context
- Key Stat:
- Genetic correlations of 0.22-0.35 between cannabis phenotypes and psychotic disorders
- Evidence Grade:
- Large-scale genetic analysis published in a top-tier journal using multiple complementary methods, though limited to European ancestry.
- Study Age:
- Published 2023
- Original Title:
- The relationship between cannabis use, schizophrenia, and bipolar disorder: a genetically informed study.
- Published In:
- The lancet. Psychiatry, 10(6), 441-451 (2023)
- Authors:
- Cheng, Weiqiu, Parker, Nadine, Karadag, Naz, Koch, Elise, Hindley, Guy, Icick, Romain, Shadrin, Alexey, O'Connell, Kevin S, Bjella, Thomas, Bahrami, Shahram, Rahman, Zillur, Tesfaye, Markos, Jaholkowski, Piotr, Rødevand, Linn, Holen, Børge, Lagerberg, Trine Vik, Steen, Nils Eiel, Djurovic, Srdjan, Dale, Anders M, Frei, Oleksandr, Smeland, Olav B, Andreassen, Ole A
- Database ID:
- RTHC-04459
Evidence Hierarchy
Watches what happens naturally without intervening.
What do these levels mean? →Frequently Asked Questions
Is the link between cannabis and psychosis genetic?
Partly. This study found significant genetic overlap between cannabis use and schizophrenia/bipolar disorder, with shared loci and bidirectional causal effects, suggesting shared biological vulnerability.
Does cannabis cause psychosis or do people with psychosis use more cannabis?
Both appear to be true. Causal analysis showed psychotic disorders increased cannabis use, and lifetime cannabis use had a causal effect on bipolar disorder specifically. The relationship runs in both directions.
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Cite This Study
https://rethinkthc.com/research/RTHC-04459APA
Cheng, Weiqiu; Parker, Nadine; Karadag, Naz; Koch, Elise; Hindley, Guy; Icick, Romain; Shadrin, Alexey; O'Connell, Kevin S; Bjella, Thomas; Bahrami, Shahram; Rahman, Zillur; Tesfaye, Markos; Jaholkowski, Piotr; Rødevand, Linn; Holen, Børge; Lagerberg, Trine Vik; Steen, Nils Eiel; Djurovic, Srdjan; Dale, Anders M; Frei, Oleksandr; Smeland, Olav B; Andreassen, Ole A. (2023). The relationship between cannabis use, schizophrenia, and bipolar disorder: a genetically informed study.. The lancet. Psychiatry, 10(6), 441-451. https://doi.org/10.1016/S2215-0366(23)00143-8
MLA
Cheng, Weiqiu, et al. "The relationship between cannabis use, schizophrenia, and bipolar disorder: a genetically informed study.." The lancet. Psychiatry, 2023. https://doi.org/10.1016/S2215-0366(23)00143-8
RethinkTHC
RethinkTHC Research Database. "The relationship between cannabis use, schizophrenia, and bi..." RTHC-04459. Retrieved from https://rethinkthc.com/research/cheng-2023-the-relationship-between-cannabis
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.