The following is a summary of “Genetic contribution to the comorbidity between attention-deficit/hyperactivity disorder and substance use disorders,” published in the March 2024 issue of Psychiatry by Koller et al.

Substance use disorders (SUDs) like cannabis use disorder (CanUD), opioid use disorder (OUD), problematic alcohol use (PAU), and problematic tobacco use (PTU) often co-occur with Attention Deficit Hyperactivity Disorder (ADHD), suggesting shared genetic factors.

Researchers conducted a retrospective study using genome-wide association studies (GWAS) summary statistics to examine the genetic architecture and causal relationships between ADHD and various SUDs.

They used GWAS summary statistics to analyze ADHD (N_eff = 51,568), CanUD (N_eff = 161,053), OUD (N_eff = 57,120), PAU (N_eff = 502,272), and PTU (N_eff = 97,836), with varying sample sizes and case definitions. Genetic correlation and latent factors contributing to ADHD and SUDs were assessed using linkage disequilibrium score regression analyses and genomic structural equations. 

The results showed a positive correlation between ADHD and CanUD, OUD, PAU, and PTU. Two latent factors were identified via genomic structural equation modeling. The two-sample Mendelian randomization analysis suggested causal effects of PAU and PTU on ADHD. Pleiotropic SNP CADM2 rs62250713 was identified between ADHD and all SUDs. We found seven, one, and twenty-eight pleiotropic variants between ADHD and CanUD, PAU, and PTU, respectively. OUD, CanUD, and PAU PRS were associated with increased odds of ADHD.

Investigators concluded that diverse genetic factors contribute to ADHD-SUD comorbidity, and there is an urgent need to understand complex genetic interactions in their relationship.

Source: sciencedirect.com/science/article/pii/S0165178124000416