An EEG approach to the neurodevelopmental hypothesis of schizophrenia studying schizophrenics, normal controls and adolescents

Based on an integrative brain model which focuses on memory-driven and EEG state-dependent information processing for the organisation of behaviour, w e used the developmental changes of the awake EEG to further investigate th e hypothesis that neurodevelopmental abnormalities (deviations in organisat ion and reorganisation of cortico-cortical connectivity during development) are involved in the pathogenesis of schizophrenia. First-episode, neurolep tic-naive schizophrenics and their matched controls and three age groups of normal adolescents were studied (total: 70 subjects). 19-channel EEG delta -theta, alpha and beta spectral band centroid frequencies during resting (b aseline) and after verbal stimuli were used as measure of the level of atta ined complexity and momentary excitability of the neuronal network (working memory). Schizophrenics compared with all control groups showed lower delt a-theta activity centroids and higher alpha and beta activity centroids. Re activity centroids (centroid after stimulus minus centroid during resting) were used as measure of update of working memory. Schizophrenics showed par tial similarities in delta-theta and beta reactivity centroids with the Ii- year olds and in alpha reactivity centroids with the 13-year olds. Within t he framework of our model, the results suggest multifactorially elicited im balances in the level of excitability of neuronal networks in schizophrenia , resulting in network activation at dissociated complexity levels, partial ly regressed and partially prematurely developed. It is hypothesised that a ctivation of age- and/or state-inadequate representations for coping with r ealities becomes manifest as productive schizophrenic symptoms. Thus, the r esults support some aspects of the neurodevelopmental hypothesis. (C) 2000 Elsevier Science Ltd. All rights reserved.