Spectral Evaluation of the Electroencephalogram: Power and Variability in Chronic Schizophrenics and Control Subjects

Selected EEG parameters were evaluated for their ability to discriminate between a group of 30 chronic schizophrenic and 30 control Ss. For each S 150 random EEG segments were collected. The results confirmed that the coefficient of variation of the absolute EEG potential recorded from the occiput is significantly (φ <.03) smaller in schizophrenics than in controls. The power density spectrum was calculated for each EEG segment. β power was significantly higher in patients, markedly so in the β2 band (34–54 Hz). The possibility of muscle contamination was considered. Coefficients of variation were calculated for the power in EEG frequency bands for each S. The most significant discriminator between schizophrenics and controls, considered to be artifact free, was the coefficient of variation of β1 (18–32 Hz) recorded from an anterior‐posterior electrode pair at the vertex (p <.0005). Included in the evaluations were: ordering of the EEG segments by delta band power, as an index of arousal; subject age; exposure to medication; and severity of illness.