Association Between Attention-Deficit/Hyperactivity Disorder and Intermittent Explosive Disorder in Youth: A Systematic Review and Meta-Analysis

This study aimed to examine the association between attention-deficit/hyperactivity disorder (ADHD) and intermittent explosive disorder (IED) or clinically comparable impulsive-aggressive phenotypes in childhood and adolescence through a systematic review and meta-analysis. PubMed, Embase, and Scopus were searched for observational studies evaluating impulsive-aggressive presentations associated with ADHD in children and adolescents. Among 7,721 records initially identified, 29 full-text articles were assessed for eligibility, 21 were included in the qualitative synthesis, and 9 met criteria for meta-analysis, comprising a total of 44,915 participants. The pooled odds ratio was 6.11 (95% CI: 5.24–7.13; p < 0.0001), with no evidence of heterogeneity (I 2 = 0%). These findings demonstrate a strong association between ADHD and intermittent explosive disorder (IED) or clinically comparable impulsive-aggressive phenotypes, with individuals with ADHD showing approximately sixfold higher odds compared with non-ADHD controls, although the certainty of the evidence should be interpreted cautiously due to indirectness and methodological variability across studies. Altered monoaminergic modulation, particularly involving dopaminergic pathways associated with reduced dopamine D2 receptor (DRD2) expression in the ventral striatum and anterior cingulate cortex, is discussed as a potential neurobiological mechanism underlying impulsive-aggressive phenotypes associated with ADHD.