Inattention in Pediatric Attention-Deficit/Hyperactivity Disorder and Anxiety: Neurophysiological Evidence for Distinct and Overlapping Cognitive Mechanisms

Abstract

Background:

Although inattention characterizes both pediatric attention deficit hyperactivity disorder (ADHD) and anxiety disorders, it is unclear whether the underlying neurocognitive mechanisms are shared or distinct. We compared behavioral performance and event-related potentials (ERPs) indexing discrete stages of attention across children with ADHD-only, Anxiety-only, co-occurring ADHD+Anxiety, and typically developing (TD) peers.

Methods:

One hundred eleven children (7–11 years) completed three computerized attention tasks while high-density electroencephalography (EEG) was recorded. Behavioral indices (accuracy, reaction time, post-error slowing) and ERP/EEG markers of attentional engagement (aperiodic exponent), stimulus discrimination (N2), action selection (P3), performance monitoring (error-related negativity; ERN) and evaluation (error positivity; Pe) were analyzed.

Results:

Relative to TD children, all clinical groups showed reduced modulation of the pre-stimulus aperiodic exponent by cognitive load and attenuated N2 amplitudes across tasks, indicating shared alterations in dynamic arousal and stimulus discrimination. Distinct patterns between the ADHD and Anxiety groups were identified at the attentional engagement, performance monitoring, and performance evaluation phases. The Anxiety-only group displayed steeper pre-stimulus aperiodic exponents preceding correct versus incorrect trials, larger ERN amplitudes relative to the ADHD+Anxiety group, and reduced Pe amplitudes relative to the TD group and ADHD+Anxiety groups, suggesting heightened error detection, but reduced conscious appraisal. In contrast, the ADHD-only group showed reduced post-error slowing, indicating weaker self-monitoring and adaptive control.

Conclusions:

Inattention in ADHD and anxiety is driven by both shared and distinct neurophysiological mechanisms. Shared alterations in early attentional engagement and stimulus processing coexist with disorder-specific differences in error monitoring and behavioral adjustment. These results position multimodal neurophysiological biomarkers as valuable tools for differential diagnosis and for guiding targeted interventions.