Genome-wide study found DNA methylation changes from cannabis use disorder in veterans, amplified by co-occurring PTSD

Four CpGs were associated with lifetime CUD after smoking adjustment: AHRR cg05575921, LINC00299 cg23079012, VWA7 cg22112841, and FAM70A cg08760398. The AHRR site remained significant even in never-smokers. CUD interacted with PTSD status: veterans with both CUD and PTSD showed significantly lower DNA methylation than those with either condition alone. Preliminary evidence suggested AHRR methylation helps explain the association between CUD and psychiatric diagnoses, particularly mood disorders.

Epigenome-wide association study in 2,310 Iraq/Afghanistan era veterans (1,109 non-Hispanic Black, 1,201 non-Hispanic White) enriched for PTSD. Analysis of lifetime CUD controlling for current smoking. CUD x PTSD interaction analysis and mediation testing.

This is the first study showing that CUD and PTSD interact epigenetically, producing greater methylation changes together than either alone. This biological synergy may explain why veterans with dual diagnoses have worse outcomes.

If CUD and PTSD amplify each other's epigenetic effects, targeted epigenetic interventions or early treatment of one condition might prevent the amplified biological changes that drive worse outcomes in dually diagnosed veterans.

Cross-sectional design cannot determine whether methylation changes are cause or consequence. Iraq/Afghanistan veteran cohort may not generalize to civilians. Blood-based methylation may not reflect brain tissue. Enrichment for PTSD may affect generalizability of CUD findings.