functional brain connectivity differences between different adhd presentations: impaired functional segregation in adhd-combined presentation but not in adhd-inattentive presentation

Introduction: contrary to diagnostic and statistical manual of mental disorders (dsm-5), fifth edition, some studies indicate that adhd-inattentive presentation (adhd-i) is a distinct diagnostic disorder and not an adhd presentation. methods: in this study, 12 adhd-combined presentation (adhd-c), 10 adhd-i, and 13 controls were enrolled and their resting state eeg recorded. following this, a graph theoretical analysis was performed and functional integration and segregation of brain network was calculated. results: the results show that clustering coefficient of theta band was significantly different among three groups and significant differences were observed in theta global efficiency between controls and adhd-c. regarding the alpha band, a lower clustering coefficient was observed in control subjects. in the beta band, clustering coefficient was significantly different between the control and children with adhd-c and also between adhd-i and adhd-c. the clustering coefficient, in the subjects with adhd-c, demonstrated a rapid decline and was significantly lower than the subjects with adhd-i and control. conclusion: decreased clustering, in high thresholds, may be associated with hyperactivity while increased segregation in low thresholds with inattentiveness. a different functional network occurs in the adhd-c brain that is consistent with several studies that have reported adhd-i as a distinct disorder.