Shared genetic factors uncovered between ADHD and cannabis addiction
- Attention-deficit hyperactivity disorder (ADHD), affecting about 5% of children and 2.5% of adults globally, is a neurodevelopmental condition marked by inattention, hyperactivity, and impulsivity.
- The research team, drawing from extensive genetic data of European ancestry, found 36 genetic loci common to both ADHD and cannabis use disorder, with significant brain-specific activity.
- Utilizing polygenic risk scores (PGS), the study revealed that individuals with ADHD in the highest risk group had an absolute 22% risk of developing cannabis use disorder, compared...
ADHD and Cannabis Use Disorders: Unraveling Their Genetic Connection
Attention-deficit hyperactivity disorder (ADHD), affecting about 5% of children and 2.5% of adults globally, is a neurodevelopmental condition marked by inattention, hyperactivity, and impulsivity. Previous research has shown individuals with ADHD are 10 times more likely to develop substance use disorders, particularly cannabis use disorder. To explore this connection, a groundbreaking study delved into the shared genetics of these conditions.
The research team, drawing from extensive genetic data of European ancestry, found 36 genetic loci common to both ADHD and cannabis use disorder, with significant brain-specific activity. In contrast, ADHD and general cannabis use shared just 10 loci, and none were consistently brain-specific. Notably, the DRD2 gene, which encodes a dopamine receptor, emerged as a shared risk factor.
Utilizing polygenic risk scores (PGS), the study revealed that individuals with ADHD in the highest risk group had an absolute 22% risk of developing cannabis use disorder, compared to just 1.6% in controls without ADHD. This risk was higher in men, who were 10% more likely to develop cannabis use disorder.
Investigating rare genetic variants, researchers found that those with both ADHD and cannabis use disorder carried a heavier burden of rare deleterious mutations, concentrated in evolutionarily tolerant genes. Importantly, the genetic overlaps differed for cannabis use disorder versus general cannabis use, indicating distinct genetic mechanisms for cannabis use as a behavior versus cannabis dependence as a disorder.
While the study’s limitations include its focus on individuals of European ancestry and the broad definition of cannabis use, it marks a significant stride in understanding the genetic links between ADHD and cannabis use disorders. By predicting individual risk, polygenic risk scores offer a promising tool for early identification and prevention strategies. Experts hope future research will refine cannabis use definitions and explore environmental factors and comorbid conditions.