Neurophysiological factors associated with cognitive deficits in children with ADHD symptoms: EEG and neuropsychological analysis

We neuropsychologically assessed cognitive deficits in 109 children with symptoms of attention-deficit/hyperactivity disorder (ADHD) and 51 children with typical development aged 7-8 years and 9-10 years and visually analyzed resting-state electroencephalography (EEG). The EEG recordings of children with ADHD more frequently contained EEG patterns of frontothalamic non-optimal functioning compared with controls, reflected by groups of bilaterally synchronous frontal theta waves (FTWs) and right hemisphere local deviations of brain electrical activity. We found cognitive impairments associated with ADHD in children with different deviations of resting-state EEG. Children with FTWs in both age groups exhibited pronounced difficulties in programming, regulation and control (executive functions), and verbal performance. Children with right hemisphere local EEG abnormalities had executive dysfunction combined with difficulties in nonverbal performance. Executive performance in typically developing children significantly improved from 7-8 to 9-10 years of age. An analysis of neuropsychological scores in children with ADHD symptoms from age 7-8 to 9-10 with the same EEG abnormalities indicated specific age-related improvement of cognitive abilities. In children whose EEG showed patterns of fronto-thalamic involvement presented significant improvement in executive and verbal performance from 7-8 to 9-10 years of age. Overcoming the same age gap in children with right hemisphere local EEG deviations significantly improved only nonverbal performance, whereas improvements in executive function were not statistically significant.