Response inhibition deficits in unmedicated youth with ADHD: An ERP/sLORETA study

Attention-Deficit/Hyperactivity Disorder (ADHD) is characterized by impairments in executive functioning, particularly response inhibition (RI). This study combines time-domain analysis and source analyses of event-related potentials (ERPs) to explore the underlying neuropsychological mechanisms of RI deficits in unmedicated youth with ADHD, and assesses ERP features as potential biomarkers to differentiate ADHD from healthy controls (HCs).

The study included 52 unmedicated youth with ADHD (ages 6-12) and 53 HCs. ERPs were recorded using an oddball paradigm, followed by within- and between-group comparisons. Source localization analysis examined regional brain activation during task performance. Significant ERP features were then used in a machine learning classification model.

Compared to HCs, youth with ADHD exhibited prolonged mismatch negativity (MMN) latency at frontal (Fz) and posterior (Pz) electrodes, and reduced latency at the central (Cz) electrode. Source analysis indicated increased activation in the cuneus and superior temporal gyrus during the MMN-deviant condition, and enhanced activation in the superior parietal lobules, inferior frontal gyrus, and rectal gyrus during the MMN-novelty condition. Additionally, ADHD patients showed higher activation in the middle temporal and middle occipital gyri during the P300-target condition, and increased activation in the superior frontal gyrus and cuneus during the P300-non-target condition. Notably, the classification model achieved an area under curve (AUC) of 0.918 using MMN latency features.

Abnormal ERP patterns in unmedicated youth with ADHD may reflect impaired RI and have potential as neurobiological markers for the disorder.