Neurocognitive Correlates of Diagnostic Heterogeneity in Children with ADHD: The Differential Contributions of Cognitive Disengagement Syndrome, Symptom Severity, and Anxiety

<b>Background/Objectives:</b> Attention-Deficit/Hyperactivity Disorder (ADHD) shows substantial cognitive heterogeneity, complicating individualized clinical formulation. This study examined whether Cognitive Disengagement Syndrome (CDS), anxiety, and ADHD symptom severity are associated with memory functions and visuospatial skills in children with ADHD. <b>Methods:</b> The sample included 120 children aged 6-12 years with ADHD (ADHD + CDS: <i>n</i> = 40; ADHD-only: <i>n</i> = 80). Memory was assessed with the Oktem Verbal Memory Processes Test (OVMPT) and Wechsler Memory Scale-Visual Reproduction (WMS-VR), and visuospatial skills with WISC-IV Block Design and Judgment of Line Orientation (JLO). ADHD symptoms were rated using combined parent-teacher Turgay-Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-Based Disruptive Behavior Disorders Scale (T-DSM-IV-S) scores; CDS symptoms with the Barkley Child Attention Scale; and anxiety with the SCARED-Child Form. Group comparisons, correlation analyses, and multivariable linear regression models were conducted. <b>Results:</b> The ADHD + CDS group performed worse on WISC-IV Block Design than the ADHD-only group (<i>p</i> = 0.005). In the ADHD + CDS group, inattention severity showed a strong negative association with WMS-VR short-term memory (<i>r</i> = -0.560, <i>p</i> < 0.001). In the ADHD-only group, inattention severity was negatively associated with OVMPT Spontaneous Recall (ρ = -0.319, <i>p</i> = 0.004) and JLO total score (ρ = -0.348, <i>p</i> = 0.002). Anxiety severity in the ADHD-only group was positively associated with OVMPT Total Learning (ρ = 0.350, <i>p</i> = 0.001), Highest Learning (ρ = 0.370, <i>p</i> = 0.001), and WMS-VR short-term memory (ρ = 0.304, <i>p</i> = 0.006). In regression analyses, the presence of CDS independently and negatively predicted WMS-VR short-term memory (β = -0.187, <i>p</i> = 0.018) and Block Design performances (β = -0.226, <i>p</i> = 0.016). Inattention symptom severity was also independently and negatively associated with Block Design performance (β = -0.243, <i>p</i> = 0.013). <b>Conclusions:</b> CDS status and symptom dimensions contribute to cognitive variability in pediatric ADHD, with CDS showing independent associations with timed visuospatial construction and short-term visual memory. Inattention severity emerged as a robust dimensional predictor of cognitive inefficiency across domains, supporting the clinical utility of symptom-based cognitive profiling in ADHD diagnostic evaluations. In addition, mild anxiety symptoms demonstrated meaningful associations with some learning and memory performances within the ADHD-only group, indicating that affective factors may modulate cognitive outcomes in ADHD. Taken together, these findings support considering CDS status and symptom dimensions jointly when characterizing cognitive variability in ADHD.