QUANTITATIVE ELECTROPHYSIOLOGICAL CHARACTERISTICS AND SUBTYPING OF SCHIZOPHRENIA

Quantitative descriptors of resting electroencephalogram (EEG) (QEEG) and event-related potentials (QERP) to visual and auditory stimuli wer e obtained from normal subjects and 94 chronic schizophrenic patients on medication, 25 chronic schizophrenics off medication, and 15 schizo phrenics with no history of medication. These schizophrenic groups sho wed a high incidence of neurometric features that were significantly d eviant from normative values. Multivariate discriminant analysis using these features successfully separated the schizophrenic patients from normals with high accuracy in independent replication. The data from the medicated group were subjected to cluster analysis. Newly develope d algorithms were used for objective selection of the most effective s et of variables for clustering and the optimum number of clusters to b e sought. Five clusters were obtained, containing roughly equivalent p roportions of the sample with markedly different QEEG profiles. The wh ole sample was then classified into these clusters. Each cluster conta ined patients both on and off medication, but patients who had never b een medicated were classified into only three of these clusters. No si gnificant clinical or demographic differences were found between membe rs of the Jive clusters; however, clear differences in QERP profiles w ere seen. These results are described in detail and possible physiolog ical and pharmacological implications are discussed.