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.