Selected quantitative EEG (QEEG) and event-related potential (ERP) variables as discriminators for positive and negative schizophrenia.

Heterogeneity is a major obstacle in the search for biological substrates in schizophrenia. The positive and negative distinction, even if too simplistic, may improve our understanding of underlying processes. Frontostriatal deficits have been related to negative symptoms, while dysfunction of the dominant temporal lobe appears more relevant to the generation of positive symptoms. Despite interactions between the subsystems, different neurophysiological profiles could be expected for patients predominantly affected at each of those levels. We performed discriminant analysis on 10 neurophysiological variables (hypothesis-related) in schizophrenic patients grouped by positive or negative symptoms (PANSS), obtaining a discriminant that correctly classified the sample. The function was then tested in a new sample of patients with schizophrenia, affective psychoses, and controls, classifying subjects with 78% sensitivity and 85% specificity. Our findings suggest that predominantly negative and positive schizophrenics have different neurophysiological profiles, which are consistent with the hypotheses of hypofrontality and temporal lobe dysfunction, respectively. A linear relation between discriminant scores and PANSS ratings might reflect coexisting pathologies or compensatory interactions in the mixed subgroup.