EEG alpha asymmetry in schizophrenia, depression, PTSD, panic disorder, ADHD and conduct disorder.

Models of laterality infer distinct aspects of EEG alpha asymmetry in clinical disorders, which has been replicated for over three decades. This biomarker now requires a more fine-grained assessment of its clinical utility as a diagnostic and treatment predictive marker. Here, within the same study we assessed resting brain laterality across six clinical disorders, for which deviant laterality has been implicated as core dysfunction. These disorders were evaluated in comparison to a large normative dataset (approximately 1,900) from the Brain Resource International Database. EEG alpha asymmetry was assessed in the frontocentral region, for resting Eyes Closed and Eyes Open conditions. Schizophrenia was characterized by significantly greater left lateralized alpha power than controls, indicating a deficit in left frontal activity at rest, which may relate to "disconnections" across wider fronto-temporal networks. The depression group showed a trend-level tendency towards the opposite pattern of greater right-lateralized activity than controls. The remaining anxiety and behavioral disorders did not show any significant deviance in alpha asymmetry from the normative control group. However, at a non-significant level laterality for these groups was generally consistent with expected directions, suggesting a propensity towards a particular lateralization but still remaining within the normative range. Overall, the results of the current study indicate that EEG alpha asymmetry may show the most clinical utility as a biomarker for schizophrenia and depression in comparison to other clinical disorders.