ADHD Symptom Severity and Oppositional Defiant Behavior: Divergent Structural Pathways Across Clinical and...

Attention-deficit/hyperactivity disorder (ADHD) affects 5%-7% of school-aged children globally and is characterized by a 40%-60% comorbidity rate with oppositional defiant disorder (ODD). Irritability has emerged as a key transdiagnostic construct linking ADHD severity to oppositional defiant behavior (ODB); however, whether the structural pattern of associations among these constructs differs across clinical and non-clinical populations remains unexamined.

This study employed multi-group path analysis within the SEM framework to test whether the structural pathways linking ADHD symptom severity, child irritability, and ODB are invariant across a Clinical ADHD Group (n = 42) and a Healthy Control Group (n = 43; total N = 85). Maternal psychological distress was controlled as an exogenous covariate across all groups.

A cross-sectional design was employed. ADHD severity, child irritability, ODB, and maternal distress were assessed via validated parent-report instruments (CPRS-R/S, ARI, BSI). Observed-variable multi-group path analysis was performed in R using the lavaan package (Rosseel, 2012) (see Supplementary Material S1 for reproducible code and fit index selection) via a nested model comparison, with omnibus structural invariance evaluated using the Chi-square difference test (Δχ²); ODB was regressed on ADHD severity, child irritability, and maternal distress, with the three exogenous variables permitted to covary. Bias-corrected bootstrapping (2000 resamples) was used for parameter confidence intervals.

The omnibus test of structural invariance was statistically significant, Δχ² (3) = 10.494, p = 0.015, indicating that the structural associations among the focal constructs differ across groups. In the Healthy Control Group, ODB was most strongly associated with child irritability (β = 0.636, p < 0.001), with ADHD severity showing a weaker association (β = 0.358, p = 0.001; R² = 0.560). In the Clinical ADHD Group, the pattern differed: ODB was most strongly associated with ADHD symptom severity (β = 0.667, p < 0.001), whereas the association with irritability was weaker (β = 0.232, p = 0.044; R² = 0.585). Maternal psychological distress was not uniquely associated with ODB in either group.

Child irritability was the strongest correlate of ODB in neurotypical children, consistent with frustration-based oppositional expression. In clinical ADHD, oppositional behavior was more strongly associated with ADHD symptom severity than with irritability, a pattern consistent with conceptualizations emphasizing executive dysfunction. These findings carry distinct assessment and intervention implications for psychiatric-mental health nursing practice.