Brain Functional Correlates of Intelligence Score in ADHD Based on EEG

Abstract

It has been shown that intelligence as a general mental ability is related to structure and function of the brain regions. However, specificity of this regional dependencies to the intelligence scores in the typical and atypical developed individuals needs to be well understood. In this study, we hypothesized that neural correlates of IQ should not have a fixed pattern rather it must follow a dynamic pattern to compensate the functional deficits caused by a neurodevelopmental disorder. Therefore, EEG correlates of normal IQ in various subtypes of attention deficit hyperactive disorder (ADHD) were compared to a group of healthy controls. Sixty-three ADHD subjects comprising of combined, inattentive, and hyperactive individuals diagnosed by a psychiatrist using structural clinical interview for DSM-V, and 46 healthy controls with similar normal IQ scores were recruited in this study. The subjects’ EEG data were then recorded during an eye-closed resting condition. The subjects’ intelligence level was measured by the Raven’s standard progressive matrices. Then, association between IQ and power of EEG signal were computed in the conventional frequency bands. Subsequently, topographical representations of these associations were compared between the groups. Our results demonstrated that association between IQ score and EEG power is not the same in various ADHD subtypes, and healthy controls. This finding suggests a compensatory mechanism in ADHD individuals for changing the regional oscillatory pattern to maintain the IQ within a normal range.