Associations between the Mismatch-negativity Potential and Symptom Severity in Medication-naive Children and Adolescents with Symptoms of Attention Deficit/hyperactivity Disorder

Objective: The mismatch negativity (MMN) event-related potential is an index of the pre-attentive stage of neural auditory information processing and an electrophysiological signal indicative of the integrity of auditory information processing with regard to the attention deficit symptom of attention deficit hyperactivity disorder (ADHD). We investigated the association between the MMN amplitude and latency in frontal brain regions and symptom severity in children with ADHD and subclinical ADHD symptoms. Methods: This study included 29 children: 16 (10 boys; mean age, 13.06 +/- 3.67 years) with ADHD (ADHD group) and 13 (eight boys; mean age, 13.40 +/- 3.31 years) with sub-clinical ADHD symptoms (subclinical ADHD group). We performed the following assessments: Korean ADHD rating scale-IV (K-ARS-IV), children depression inventory, state/trait anxiety inventory for children, and MMN (measured at Fz, FCz, Cz, and CPz). Results: There were no sex or mean age differences between the groups (chi(2) = -0.01, p = 0.958; Z = -1.88, p = 0.060, respectively). The ADHD group had a significantly higher mean K-ARS-IV score (26.13 +/- 9.56 vs. 17.15 +/- 11.73, Z = -2.11, p = 0.035). Significant differences were found according to symptom severity in the MMN amplitude at FCz (Z = -2.11, p = 0.035) and MMN latency at Fz and FCz (Z = -2.48, p = 0.013; Z = - 2.57, p = 0.010). The K-ARS-IV, K-ARS inattention subscale, and K-ARS hyperactivity-impulsivity subscale scores in the ADHD group correlated significantly with the MMN amplitude at Cz and CPz. Conclusion: This study found differences in the MMN amplitude and latency according to the severity of ADHD symptoms and identified MMN as a potential adjunct to the diagnosis of ADHD.