A shared low-frequency oscillatory rhythm abnormality in resting and sensory gating in schizophrenia

ObjectivesWe hypothesized that an oscillatory abnormality that is consistently observed across various testing paradigms may index an elementary neuronal abnormality marking schizophrenia risk.MethodsCompared neural oscillations in resting EEG and sensory gating conditions in schizophrenia patients (n = 128), their first-degree relatives (n = 80), and controls (n = 110) and calculated phenotypic and/or genetic correlation of the abnormal measure across these conditions.ResultsUsing a uniform, single trial analytical approach, we identified two prominent oscillatory characteristics in schizophrenia: (1) augmented neural oscillatory power was pervasive in medicated schizophrenia patients in most frequencies, most prominent in the theta–alpha range (4–11 Hz) across the two paradigms (all p < 0.007); and (2) their first-degree relatives shared significantly augmented oscillatory energy in theta–alpha frequency in resting (p = 0.002) and insufficient suppression of theta–alpha in sensory gating (p = 0.01) compared with normal controls. Heritability estimates for theta–alpha related measures for resting and gating conditions ranged from 0.44 to 0.49 (p < 0.03). The theta–alpha measures were correlated genetically with each other (RhoG = 0.82 ± 0.43; p < 0.05).ConclusionsAugmented theta–alpha rhythm may be an elementary neurophysiological problem associated with genetic liability of schizophrenia.SignificanceThis finding helps to refine key electrophysiologic biomarkers for genetic and clinical studies of schizophrenia.

► Compared single trial based neural oscillations in resting EEG and pair-click auditory evoked potentials in schizophrenia patients and their families. ► Augmented theta–alpha range oscillations in resting EEG, and less suppression of the same band in the pair-click paradigm were the only abnormal oscillatory components shared by medicated schizophrenia patients and their unmedicated, non-ill first-degree relatives. ► The theta–alpha measures for resting and pair-click conditions were heritable and also genetically correlated, suggesting that abnormally augmented theta–alpha rhythm may be an elementary neurophysiological problem associated with genetic liability of schizophrenia.