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

OBJECTIVES: We hypothesized that an oscillatory abnormality that is consistently observed across various testing paradigms may index an elementary neuronal abnormality marking schizophrenia risk.
METHODS: Compared 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.
RESULTS: Using 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).
CONCLUSIONS: Augmented theta-alpha rhythm may be an elementary neurophysiological problem associated with genetic liability of schizophrenia. SIGNIFICANCE: This finding helps to refine key electrophysiologic biomarkers for genetic and clinical studies of schizophrenia.