Introduction As numerous studies have shown, executive dysfunction is the main impairment in attention‐deficit/hyperactivity disorder. According to recent neuroimaging studies, the frontoparietal coherence plays a key role in overall cognitive functions. Therefore, the aim of this study was to compare executive functions during resting‐state EEG by monitoring brain connectivity (coherence) patterns in children with attention deficit hyperactivity disorder (ADHD) with or without reading disability (RD). Methods The statistical sample of the study consisted of 32 children with ADHD aged between 8 and 12 years old with or without specific RD. Each group consisted of 11 boys and 5 girls that were matched on chronological age and gender. EEG was recorded during eyes‐opened condition and brain connectivity within and between frontal and parietal regions was analyzed within theta, alpha, and beta bands. Results The results revealed that across the frontal regions, the comorbid group showed a significant reduction in the left intrahemispheric coherence in the alpha and beta bands. The ADHD‐alone group exhibited increased theta and decreased alpha and beta coherence in frontal regions. In the frontoparietal regions, children in the comorbid group showed lower coherence between frontal and parietal networks compared to children without comorbid RD. Conclusion The findings indicate that brain connectivity (coherence) patterns of children with ADHD with comorbid RD were more abnormal and lend support to more disrupted cortical connectivity in the comorbid group. Thus, these findings can be a useful marker for better recognizing ADHD and comorbid disabilities.

Recent neuroimaging studies have shown that main symptoms of Autism Spectrum Disorder (ASD) such as deficits in social communication, speech and repetitive behaviors are associated with abnormalities in neural connectivity. The abnormalities in neural connectivity have been studied by several methods. Among these methods, electroencephalography is an efficient and a non-invasive tool that records brain electrical activity and helps us to gain information about brain neural connectivity and cognitive characters. Therefore, the purpose of this study was to analyze electroencephalogram resting state data to compare brain connectivity (coherence) patterns between children with ASD and typically developing children. The method of this study was descriptive-analytical. The population of the study consisted of all children with ASD (aged 6-13) referred to psychologists in Mehraz Andisheh Clinic in Shiraz. Fifteen children with ASD (boys = 11 and girls = 4) were selected via purposeful sampling method. Moreover, a group of fifteen typically developing children who were matched based on chronological age and gender were recruited. Quantitative Electroencephalography data analyses showed a significant difference between the two groups and indicating hyper connectivity in most frequency bands among children with ASD. Therefore, quantitative electroencephalography patterns of children with ASD indicated an increase in the levels of coherence in delta (p < .05) and theta (p < .05) powers in the prefrontal region, theta (p < .05) and alpha (p < .05) waves in the central region, in theta (p < .001), alpha (p < .001) and beta (p < .001) waves in the occipital region, in addition to delta (p < .001), theta (p < .001) and alpha (p < .001) waves in the temporal region. The findings demonstrated abnormalities in brain connectivity (coherence) patterns of children with ASD which is supported by cortical connectivity theory. Consequently, these findings (hyper connectivity patterns) can be considered as a useful marker to better diagnose ASD. Moreover, changing these patterns may have a positive impact on the treatment of individuals with ASD.