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P300 alterations in schizophrenic patients experiencing auditory hallucinations
Charalabos Papageorgiou1, Panayiotis Oulis, Christos Vasios
1Psychophysiology Laboratory, Department of Psychiatry, Eginition Hospital, University of Athens, 74 Vas. Sophias Ave., Athens, 11528, Greece. panchris@otenet.gr
Summary
Auditory hallucinations in schizophrenia are linked to attention deficits, measurable by P300 event-related potentials (ERPs). Treatment with clozapine or olanzapine improved P300 amplitude and attention, though memory performance remained impaired.
Area of Science:
- Neuroscience
- Psychiatry
- Cognitive Psychology
Background:
- Attentional deficits are key in schizophrenia pathophysiology, particularly in auditory hallucinations.
- The P300 event-related potential (ERP) measures stimulus classification speed (latency) and attentional resource allocation (amplitude).
Purpose of the Study:
- To compare P300 ERPs in healthy subjects and schizophrenic patients with auditory hallucinations.
- To assess the effects of clozapine and olanzapine treatment on P300 ERPs and attention in schizophrenia.
Main Methods:
- Auditory P300 was measured during a memory test in 16 male schizophrenic patients and 13 male controls.
- Patients were re-assessed after hallucination remission following treatment with clozapine (8) or olanzapine (8).
Main Results:
- Hallucinating patients showed reduced P300 amplitude compared to controls and during remission.
- Left temporoparietal and prefrontal areas were critical for differentiating patient groups.
- Memory performance improved with treatment but remained below healthy controls.
Conclusions:
- Auditory hallucinations in schizophrenia involve attention abnormalities mediated by left temporoparietal and prefrontal networks.
- Clozapine and olanzapine treatments improved attentional function in hallucinating schizophrenic patients.