Reduced prefrontal response control in patients with schizophrenias: a subgroup analysis.

We investigated the function of the anterior cingulate cortex (ACC) with the continuous performance test (CPT) in patients with chronic schizophrenias. We had previously shown that the NoGo anteriorisation (NGA), which consists of a more anterior center of gravity (centroid) of the event-related potentials during the inhibition of a prepared motor response, correlates with physiological activation of the ACC in healthy probands. However, in patients with schizophrenias, the event-related potentials are located more anteriorly in the Go condition and more posteriorly in the NoGo condition, which leads to a decreased NGA reflecting reduced activation of the ACC. We now extend our observations to a larger number of patients with different subgroups of chronic schizophrenias according to Leonhard's classification system. While the schizophrenic patients as a group showed only a trend towards a decreased NGA, there was a significant reduction of the NGA in patients with systematic schizophrenias but not in those with unsystematic schizophrenias. Our results show that a subclassification of "schizophrenic" patients is useful to detect differences between subgroups, which may reflect differences in pathophysiology.