Decreased functional connectivity of EEG theta-frequency activity in first-episode, neuroleptic-naive patients with schizophrenia: preliminary results

We explored and refined the hypothesis that during a first episode of acute schizophrenia a disorganization of brain functioning is present. A novel E EG measure was introduced, Global Field Synchronization (GFS), that estimat es functional connectivity of brain processes in different EEG frequency ba nds. The measure was applied to EEG's from 11 never-treated, first-episode, young patients with an acute, positive, schizophrenic symptomatology and f rom 19 controls, residing in Bern, Switzerland. In comparison to age- and s ex- matched controls, patients had significantly decreased GFS in the theta EEG frequency band, indicating a loosened functional connectivity of proce sses in this frequency. The result was confirmed in an independent, compara ble patient group from Osaka, Japan (9 patients and 9 controls), thus makin g a total of 20 analyzed patients. Previous EEG research in healthy, awake subjects indicated a positive correlation of theta activity with memory fun ctions. Thus, our result suggests a loss of mutual interdependence of memor y functions in patients with acute schizophrenia, which agrees well with pr evious reports of working memory dysfunction in schizophrenia. (C) 2001 Els evier Science B.V. All rights reserved.