EEG coherence and syndromes in schizophrenia

Background Frith et al (1995) and others have hypothesised that disruptions in the connection between left frontal and temporal areas of the brain are a central deficit in schizophrenia. In this paper we examine whether such connectivity as assessed by EEG coherence is related to level of symptoms in patients with schizophrenia. Method For 73 patients with schizophrenia, assessments of the EEG coherence between frontal and temporal regions were carried out under conditions of activation by a mathematical task, and between frontal and occipital regions when performing a visuo-spatial task. We then examined the relationship between these coherence measures and the reality distortion, disorganisation and psychomotor poverty dimensions of symptomatology. Results Only left frontal-temporal connectivity was found to have a significant negative relationship to symptomatology. This relationship was, however, specific to reality distortion rather than to symptoms of disorganisation or psychomotor poverty, and may be more characteristic of males than females. Conclusions Disruption of frontal temporal connectivity appears to have a specific relationship to reality distortion symptoms in schizophrenia.