Group Independent Component Analysis (gICA) and Current Source Density (CSD) in the study of EEG in ADHD adults

• ADHD adults showed reduced EEG activity in the different frequency ranges as compared with healthy subjects.
• Spatial pattern of differences depended on whether the eyes were open or closed.
• gICA and CSD approaches are probably more sensitive for differentiating the characteristics of EEG spectra in groups of patients/subjects, as compared to spectral analysis of EEG.

ObjectiveTo investigate the performance of the spectral analysis of resting EEG, Current Source Density (CSD) and group independent components (gIC) in diagnosing ADHD adults.MethodsPower spectra of resting EEG, CSD and gIC (19 channels, linked ears reference, eyes open/closed) from 96 ADHD and 376 healthy adults were compared between eyes open and eyes closed conditions, and between groups of subjects.ResultsPattern of differences in gIC and CSD spectral power between conditions was approximately similar, whereas it was more widely spatially distributed for EEG. Size effect (Cohen’s d) of differences in gIC and CSD spectral power between groups of subjects was considerably greater than in the case of EEG. Significant reduction of gIC and CSD spectral power depending on conditions was found in ADHD patients. Reducing power in a wide frequency range in the fronto-central areas is a common phenomenon regardless of whether the eyes were open or closed.ConclusionsSpectral power of local EEG activity isolated by gICA or CSD in the fronto-central areas may be a suitable marker for discrimination of ADHD and healthy adults.SignificanceSpectral analysis of gIC and CSD provides better sensitivity to discriminate ADHD and healthy adults.