EEG alpha coherence and psychopathological dimensions of schizophrenia

The aim of this study was to evaluate the correlation between psychopathological dimensions in recent-onset neuroleptic-naive schizophrenic patients and EEG alpha coherence in the resting state. 37 neuroleptic-naive recent-onset schizophrenic patients were assessed on the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms, and psychopathological dimension scores on reality distortion, psychomotor poverty and disorganization were calculated. EEG alpha coherence was computed across 14 intra-hemispheric and 8 interhemispheric electrode pairs in the resting eyes closed and eyes open conditions. The relationship between the psychopathological dimension scores and coherence values was assessed using Pearson's product moment correlation with Bonferroni correction for levels of significance. Significant associations between higher psychomotor poverty scores and lower inter-hemispheric coherence values were found across the central and parietal regions in the eyes closed condition and across central regions in the eyes open condition. Reality distortion and disorganization dimensions were not significantly correlated with intra- or inter-hemispheric coherences in both eyes closed and eyes open conditions. However there was a trend for an inverse correlation between disorganization dimension and intra-hemispheric coherence across left frontal, left temporo-parietal and right parieto-occipital regions in the eyes open condition. These findings suggest a possible differential pattern in the extent of brain involvement across the three psychopathological dimensions of schizophrenia in neurolepticnaive patients with recent-onset illness.