Using advanced causal modeling on 637 adolescents from the IMAGEN study, researchers found a directional relationship from cannabis use to accelerated prefrontal cortical thinning, consistent with cannabis adversely affecting brain development.
Neuroscientists studying adolescent brain development; parents and educators; policymakers considering youth cannabis regulations.
All BCN algorithms pointed from cannabis use to cortical thinning
What the researchers found
All Bayesian causal network algorithms strongly suggested a directional relationship from adolescent cannabis use to accelerated cortical thinning in the prefrontal cortex, even after accounting for demographics, psychopathology, childhood adversity, and other substance use.
Why it matters
Most evidence linking cannabis to brain changes is correlational. This study applies specialized statistical methods designed to detect causal direction, and the results consistently point from cannabis use to brain thinning rather than the reverse. This strengthens the case that cannabis genuinely affects adolescent brain development.
The numbers in context
637 adolescents who were cannabis-naive at age 14. All BCN algorithms pointed from cannabis use to cortical thinning. Analysis controlled for demographics, psychopathology, childhood adversity, and other substance use.
How the study worked
Bayesian causal network modeling applied to 637 cannabis-naive adolescents from the IMAGEN study who were followed from age 14. The analysis incorporated cannabis use, prefrontal cortical thickness, demographics, psychopathology, childhood adversity, and other substance use to determine the most probable directional relationships.
What this study cannot tell us
Bayesian causal modeling provides evidence for probable causal direction but does not constitute definitive proof of causation. The sample was primarily European adolescents. Other unmeasured confounders could still be driving the association.
How to read the evidence
Moderate: sophisticated causal modeling on a well-characterized longitudinal cohort, but BCN modeling has inherent limitations in proving causation.
When this study was published
Published in 2022.
The bigger picture
This builds on the same IMAGEN cohort that previously showed the correlation between cannabis and cortical thinning. By adding causal modeling, it moves the evidence closer to demonstrating causation, aligning with animal studies that show THC disrupts cortical development.
Questions still open
- At what frequency or dose of cannabis use does cortical thinning become detectable? Is the thinning reversible if cannabis use stops during adolescence? Do the brain changes translate to measurable cognitive or functional consequences?
Common questions
Does this prove cannabis causes brain damage in teenagers?
What is cortical thinning?
Read the original research
Bayesian causal network modeling suggests adolescent cannabis use accelerates prefrontal cortical thinning.
Translational psychiatry, 12(1), 188
Citation
Owens, Max M; Albaugh, Matthew D; Allgaier, Nicholas; Yuan, Dekang; Robert, Gabriel; Cupertino, Renata B; Spechler, Philip A; Juliano, Anthony; Hahn, Sage; Banaschewski, Tobias; Bokde, Arun L W; Desrivières, Sylvane; Flor, Herta; Grigis, Antoine; Gowland, Penny; Heinz, Andreas; Brühl, Rüdiger; Martinot, Jean-Luc; Martinot, Marie-Laure Paillère; Artiges, Eric; Nees, Frauke; Orfanos, Dimitri Papadopoulos; Lemaitre, Herve; Paus, Tomáš; Poustka, Luise; Millenet, Sabina; Fröhner, Juliane H; Smolka, Michael N; Walter, Henrik; Whelan, Robert; Mackey, Scott; Schumann, Gunter; Garavan, Hugh. (2022). Bayesian causal network modeling suggests adolescent cannabis use accelerates prefrontal cortical thinning.. Translational psychiatry, 12(1), 188. https://doi.org/10.1038/s41398-022-01956-4
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