Overton Da

Correlations between psychiatric diagnosis and some quantitative EEG variables.

Several methods of quantitative analysis were applied to the left parietal resting EEGs of 48 nonpatient controls and 90 undrugged psychiatric inpatients. Patient and control groups, matched for age and sex, differed as follows: (a) Mean frequency was lower and frequency variability was greater in the total patient group than in controls. (b) Mean amplitude was higher and mean frequency lower in chronic schizophrenics than in controls; the amplitude differences were contributed mainly by female patients. (c) Amplitude and frequency means of nonpsychotic patients were intermediate between those of chronic schizophrenics and controls. (d) Mean amplitudes were greater and frequency variability was less in neurotics than in controls.

Psychiatric Diagnosis and EEG-Evoked Response Relationships

This study was conducted to determine whether the patterning of EEG and somatosensory evoked response (SER) variables, as determined by the correlations between them, differs with respect to psychiatric diagnosis. Subjects were 43 nonpatients and 90 psychiatric inpatients. SER modified recovery function recordings provided 36 variables, reflecting amplitude and its variations with different stimulus conditions. A 10-min left parietal EEG was quantitatively analyzed to give mean amplitude and frequency and variability measures. Correlations between EEG and ER variables were compared both for unmatched groups of nonpatients, schizophrenics, psychotic depressions, and nonpsychotics and for smaller age and sex-matched diagnostic groups. The results revealed a number of correlation differences between clinical groups. The nature of the differences suggested diagnostic specificity for EEG-ER patterning, which may provide a new, psychiatrically relevant electrophysiological variable.