Theta-phase gamma-amplitude coupling as a neurophysiological marker of attention deficit/hyperactivity disorder in children

Theta-phase gamma-amplitude coupling (TGC) between slow and fast oscillations is considered to represent cortico-subcortical interactions. The purpose of this electroencephalographic (EEG) study was to evaluate the diagnostic utility of TGC by comparing the power spectra and TGC at rest between ADHD and control children. Nineteen-channel EEGs were recorded from 97 volunteers (including 53 subjects with ADHD attending a camp for hyperactive children). The EEG power spectra and TGC data were analyzed. Analysis of covariance (ANCOVA) was conducted on the quantitative EEG results between the groups to adjust for sex. Receiver operator characteristic (ROC) analysis was conducted to examine the discriminating ability of each parameter for ADHD diagnosis. The ADHD group exhibited significantly decreased TGC in multiple areas, including frontal (Fp1, F3, F7, F6), temporal (T3), and occipital (O2) areas, compared with the control group. The ROC analysis performed on the TGC data generated the most accurate result among the EEG measures, with an overall classification accuracy of 71.7%. TGC, which reflects the degree of neuronal interactions between functional systems, provides information about an individual's attentional network. Therefore, resting-state TGC is a promising neurophysiological marker of ADHD in children.