Intra and inter-hemispheric changes in alpha intensities in EEGs of schizophrenic patients versus matched controls.

62 EEGs of 5 min recordings, over C4-P4, P4-02, C3-P3, P3-01, have been recorded from 31 schizophrenic patients and 31 controls, matched for age (27 years) and sex (males). Patients were clinically classified into 3 sub-groups: paranoid-type P(7), residual type R(10) and others O(14). Controls were statistically classified into 2 sub-groups as high alpha subjects HA(15) or low alpha subjects LA(16). Following computer Fourier statistical analysis, evolutive power spectra, averaged power spectra and spectral variances were obtained for each EEG recording. Date reduction provided for each EEG: Mean frequencies, mean amplitudes in microvolts and percentage asymmetries, resonance, spectral parameters; theta/alpha, with their variabilities. Power spectra were averaged between patients or between subjects for each sub-group. The alpha peak and the mean RMS amplitude was higher over P3-01 than over P4-02 for the residual-type of schizophrenic patients, when compared to his matched control sub-group of high-alpha subjects which presented almost symmetrical occipital alpha peaks and RMS amplitudes. However, the most important changes appear to be intra-hemispheric. The alpha peaks and RMS amplitudes were almost equal between C3-P3 and P3-O1 for the paranoid type of schizophrenic patients in contrast to other sub-groups and especially both control sub-groups. This seems to imply left hemispheric changes in terms of EEG spectral alpha intensities, when tracings of schizophrenics were compared with recordings of volunteers.