Cortical hypoactivation of frontal areas modulate resting EEG microstates in children with ADHD.

Background: The present study examined EEG microstate alterations and their neural generators during resting state in children with ADHD to explore a potential state biomarker.

Methods: A total of seventy-six participants, thirty-eight each, combined type ADHD, and neurotypical children (NC) participated in the study. Five-minute resting (eyes open) 128 channel eeg data were acquired and two-minute clean EEG data were analyzed for microstates, its sources and connectivity in both the groups. Between groups comparisons were done for microstate parameters using modified k means clustering in Cartool software. Further, the cortical sources and functional connectivity of significant microstate maps were explored using LORETA software. Subsequently microstate parameters were correlated with the behavioral scores from Conner's parent rating scale.

Results: Among the microstate parameters examined, children with ADHD displayed significant difference (p<0.05) in time frames and time coverage of map B (decreased) and transition probability of map D (increased) respectively. Interestingly, source analysis of both microstate maps showed hypoactivation of frontal areas predominantly while functional connectivity showed hyperconnectivity between medial frontal gyrus and anterior cingulate gyrus (executive function area) for map B and hypoconnectivity between medial frontal gyrus and middle temporal gyrus (both are suggested to be part of DMN areas) for map D. Further CSD values of map B was found to be correlated with executive function scores of conners questionnaire.

Conclusion: EEG microstate features, alongside source and connectivity measures, could discern children with ADHD from neurotypical controls. The hypoactivation of predominantly frontal areas and its connectivity was found to determine microstate maps.