First-episode schizophrenics show normal duration and topography of quasistationary EEG segments as compared to controls, during rest as well as during active tasks

In patients suffering from chronic schizophrenia, both altered temporospati al structure of the EEG and impaired activation during cognitive tasks have repeatedly been demonstrated. The present study evaluates whether similar abnormalities are present in drug-naive first-episode schizophrenics. The E EGs of 32 schizophrenic patients and of 52 healthy controls were recorded d uring a simple and a complicated motor task, a simple and a complicated aud itory stimulus, and during resting periods between the tasks. The temporosp atial characteristics were evaluated by adaptive segmentation of EEG, which decomposes an EEG into temporal segments of quasistationary activity. No d ifferences in the temporal and topographic aspects of the EEGs were found b etween the first-episode schizophrenic patients and the controls, neither d uring the resting EEGs nor during active tasks. Moreover, the dynamic cours e of the EEGs, defined as the alternation between task-related changes of t emporospatial patterns and the reappearance of resting patterns, was identi cal in patients and controls. The present findings suggest that while abnor mal EEG power spectra seem a consistent finding in treated as well as in ne ver-treated schizophrenics, altered temporospatial patterns and reduced tas k-related EEG changes are inconsistent signs. (C) 1999 Elsevier Science Ire land Ltd. All rights reserved.