Endocannabinoid gene interactions were linked to alcohol use disorder risk in European teens | Research

The takeaway

Gene-gene interactions among endocannabinoid system genes (CNR1, MGLL, DAGLA) were associated with alcohol use disorder risk in European adolescents, with partial replication in a Canadian cohort.

Behavioral geneticists, addiction researchers, adolescent health specialists

3-SNP interaction across CNR1, MGLL, and DAGLA predicted alcohol disorder risk

What the researchers found

Two SNPs were significantly associated with positive AUDIT screens after correction: rs9353525 in CNR1 (OR=0.73) and rs507961 in MGLL (OR=0.78). A three-SNP interaction model involving MGLL, DAGLA, and CNR1 predicted case-control status after correcting for covariables. This interaction showed a trend toward replication in the Canadian SYS cohort (BETA=0.501, p=0.06).

Why it matters

The endocannabinoid system is primarily associated with cannabis effects, but these findings suggest it also plays a role in alcohol use disorder risk, potentially through shared reward pathway modulation. This has implications for understanding cross-substance vulnerability.

The numbers in context

IMAGEN: n=2,051 European adolescents; SYS: n=772 Canadian adolescents; rs9353525 (CNR1) OR=0.73, p=0.042; rs507961 (MGLL) OR=0.78, p=0.043; 3-SNP interaction model p=0.006; replication trend BETA=0.501, p=0.06

How the study worked

Set-based gene testing and SNP-level analysis in 2,051 European adolescents (14-18) from the IMAGEN study, with replication attempted in 772 Canadian adolescents from the Saguenay Youth Study. AUDIT score >7 defined case status. Generalized multifactor dimensionality reduction analyzed gene-gene interactions.

What this study cannot tell us

Preliminary findings with modest effect sizes. Replication in the Canadian cohort only reached trend-level significance (p=0.06). AUDIT screening is not equivalent to clinical diagnosis. European-ancestry cohorts limit generalizability.

How to read the evidence

Well-designed genetic study with two cohorts, but modest effect sizes and only trend-level replication make findings preliminary.

When this study was published

Published in 2021.

The bigger picture

Finding that endocannabinoid genes contribute to alcohol disorder risk through gene-gene interactions suggests the endocannabinoid system may be a common vulnerability pathway for multiple substance use disorders, not just cannabis-related ones.

Questions still open

Would these genetic interactions also predict cannabis use disorder or polysubstance use? Could endocannabinoid system-targeted medications help prevent alcohol use disorder in genetically vulnerable adolescents?

Common questions

What are endocannabinoid genes?

These are genes that code for components of the endocannabinoid system, including cannabinoid receptors (CNR1) and enzymes that produce or break down endocannabinoids (DAGLA, MGLL). Variants in these genes can affect how the system functions.

Why would cannabis-related genes affect alcohol risk?

The endocannabinoid system modulates reward circuitry in the brain that responds to multiple substances, not just cannabis. Genetic variation in this system could alter reward sensitivity broadly, affecting vulnerability to alcohol and potentially other substances.

Read the original research

Endocannabinoid Gene × Gene Interaction Association to Alcohol Use Disorder in Two Adolescent Cohorts.

Frontiers in psychiatry, 12, 645746

View on PubMed ↗Publisher’s paper ↗

Citation

Elkrief, Laurent; Spinney, Sean; Vosberg, Daniel E; Banaschewski, Tobias; Bokde, Arun L W; Quinlan, Erin Burke; Desrivières, Sylvane; Flor, Herta; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Brühl, Rüdiger; Martinot, Jean-Luc; Paillère Martinot, Marie-Laure; Nees, Frauke; Papadopoulos Orfanos, Dimitri; Poustka, Luise; Hohmann, Sarah; Millenet, Sabina; Fröhner, Juliane H; Smolka, Michael N; Walter, Henrik; Whelan, Robert; Schumann, Gunter; Pausova, Zdenka; Paus, Tomáš; Huguet, Guillaume; Conrod, Patricia. (2021). Endocannabinoid Gene × Gene Interaction Association to Alcohol Use Disorder in Two Adolescent Cohorts.. Frontiers in psychiatry, 12, 645746. https://doi.org/10.3389/fpsyt.2021.645746