Different executive function impairments in medication-naïve children with attention-deficit/hyperactivity disorder comorbid with oppositional defiant disorder and conduct disorder

The impairment of executive functions (EFs) in attention-deficit/hyperactivity disorder (ADHD) might vary from one individual to another, indicating high heterogeneity. Comorbidity may contribute to this heterogeneity. Disruptive behavior disorders (DBD), including oppositional defiant disorder (ODD) and conduct disorder (CD), is the most common comorbidity in ADHD. Although many studies suggest that ADHD with CD (ADHDCD+) and ADHD with ODD (ADHDODD+) should be treated differently, little research has attempted to separate these two disorders when studying the EFs and brain imaging of ADHD with DBD (ADHDDBD+). Thus, based on our ongoing research in ADHD, we have now recruited a large sample size of medication-naïve children to obtain estimates of neurocognitive function and functional brain networks. We found no EF impairment in ADHDCD+ patients compared with healthy controls (HCs). Correlation analysis showed that more severe CD symptoms were associated with better EFs. The mediation analysis revealed that the relationship between CD symptoms and inhibition function was mediated by the functional connectivity (FC) of SMN(L) - DMN(R) in the younger group. The study suggested that ADHDCD+ and ADHDODD+ are different in their EF impairment. The comorbidity of CD may not worsen the impairments and might even improve EF performance within ADHD individuals.