Increase of P300-NoGo-anteriorisation in first-episode schizophrenia patients during Continuous Performance Test

Objectives: It was found that in chronic schizophrenia patients the NoGo anteriorisation (NGA) in a cued Continuous Performance Test (CPT) was markedly reduced. Our study was performed to reproduce this result in first-episode schizophrenic patients by microstate (MS) analysis. Methods: 18 schizophrenic patients, half were medicated with antipsychotics, and 18 healthy subjects matched for gender and age were investigated with a cued CPT. Event related potentials (ERP) were recorded with 21 EEG-channels. Go trials must be answered by pressing a button. In each subject Go- and NoGo-average ERP-maps were clustered into 5 topographical MS-classes. At MS-maximum the positive centroids of the Go- and NoGo-maps and their distance, the NGA, were determined Results: In schizophrenia patients the following significant effects were found: Increase of NGA, reaction time and NoGo-latency as well as decrease of Go- and NoGo-amplitudes and NoGo-MS-duration. Beginning of NoGo-MS was retarded. The increase of NGA was not induced by antipsychotics. Conclusions: Whereas most of the P300-parameters reflecting attention are typically decreased already in first-episode schizophrenia patients, frontal function represented by the increase of NGA seems to be intact in first-episode but decreases during chronification of schizophrenia. It is discussed, whether in the initial phase of schizophrenia prevention of psychotic episodes could decrease or prevent the progression of cognitive impairment.