Reduced frontal asymmetry of delta waves during all-night sleep in schizophrenia.

Delta wave deficits during sleep have been observed in patients with schizophrenia. Decreased slow-wave sleep is reported to be associated with negative symptoms. Frontal lobe dysfunction is also believed to underlie negative symptoms of schizophrenia. This study was designed to identify functional abnormalities in schizophrenia manifested on patients' electroencephalograms. Polysomnograph examinations were performed in 12 healthy male volunteers and 11 male outpatients with schizophrenia. We investigated the laterality of frontal cortical delta waves in patients with schizophrenia and in healthy control subjects. Laterality of frontal cortex delta wave counts during all-night sleep was investigated by computer analysis. Total delta wave counts were lower in patients with schizophrenia than in control subjects. Control subjects showed significantly higher delta wave counts in the right frontal cortex than in the left. This asymmetry was not observed in patients with schizophrenia. These findings suggest that reduced right frontal delta wave dominance is involved in the pathophysiology of schizophrenia.