A methylome-wide study of 703 adolescents found cannabis use associated with specific DNA methylation changes, including patterns in T cells and monocytes that overlap with brain tissue findings from psychosis research.
Epigenetics researchers, adolescent mental health professionals, cannabis and psychosis researchers
Cannabis-associated methylation in immune cells overlaps with psychosis-related brain findings
What the researchers found
45 significant methylation sites were identified in whole blood, plus 32 additional in cell-type analyses. B-cell methylation overlapped with genetic studies of educational attainment and intelligence. T-cell and monocyte results overlapped with brain tissue methylation findings from psychosis studies.
Why it matters
This provides the first epigenomic evidence linking adolescent cannabis use to molecular changes that overlap with psychosis-related pathways, offering a potential biological mechanism for the cannabis-psychosis association.
The numbers in context
703 adolescent samples; 45 significant whole-blood CpGs; 32 additional cell-type-specific CpGs; significant overlap with psychosis and intelligence genetic studies
How the study worked
Methylome-wide association study using enrichment-based sequencing in 703 adolescent samples from the Great Smoky Mountain Study, with cell-type-specific analyses for granulocytes, T cells, B cells, and monocytes.
What this study cannot tell us
Blood methylation may not directly reflect brain methylation. Cross-sectional design cannot determine whether methylation changes preceded or followed cannabis use. The Great Smoky Mountain Study has specific demographic characteristics.
How to read the evidence
Large methylome-wide study with novel cell-type-specific analyses, though cross-sectional
When this study was published
Published in 2021. Epigenomic studies of cannabis effects are a rapidly emerging field.
The bigger picture
The overlap between cannabis-associated methylation and psychosis-related findings in brain tissue suggests that cannabis may partly increase psychosis risk through epigenetic modifications to immune and inflammatory pathways.
Questions still open
- Do these methylation changes reverse with cannabis cessation? Can methylation patterns predict which adolescent cannabis users will develop psychosis? Are these changes dose-dependent?
Common questions
Does cannabis change DNA in adolescents?
How does this relate to psychosis risk?
Read the original research
Methylomic Investigation of Problematic Adolescent Cannabis Use and Its Negative Mental Health Consequences.
Journal of the American Academy of Child and Adolescent Psychiatry, 60(12), 1524-1532
Citation
Clark, Shaunna L; Chan, Robin; Zhao, Min; Xie, Lin Y; Copeland, William E; Aberg, Karolina A; van den Oord, Edwin J C G. (2021). Methylomic Investigation of Problematic Adolescent Cannabis Use and Its Negative Mental Health Consequences.. Journal of the American Academy of Child and Adolescent Psychiatry, 60(12), 1524-1532. https://doi.org/10.1016/j.jaac.2021.02.008
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