A small P300 component of the auditory event-related potential has been found to predict poor clinical outcome with a higher amount of thought disorders in schizophrenia and has been proposed as a ...marker for an underlying neurodevelopmental disorder with prominent thought disorders, early age of onset, prominent negative symptoms and positive family history. The present study was designed to confirm our previous findings with subcomponent analysis. Using dipole source analysis a temporo-basal (TB) P300 as well as a temporo-superior (TS) P300 and LP potential were separated. Fifty patients with schizophrenia (DSM-IV) were included in the study. Late auditory event-related P300 potentials were recorded to infrequent auditory stimuli after treatment psychopathology and family history were assessed. The TB-P300 amplitudes were significantly negatively correlated with thought disorders remaining after treatment and were positively correlated with age of onset. Illness duration was significantly correlated to TB-P300 and TS-P300 amplitudes in the group of patients with late onset. No significant correlations were found with negative symptoms. Family history did not show significant effects on P300. A smaller P300 in patients with more thought disorder remaining after stabilization on medication and an earlier age of onset support the hypothesis that P300 characterizes schizophrenic patients with an underlying neurodevelopmental disorder with specific clinical symptom clusters. On the other hand, diminished P300 with illness duration in the group of patients with later age of onset supports an underlying neurodegenerative progressive process in this subgroup of patients.
Corpus callosum and P300 in schizophrenia Frodl, Thomas; Meisenzahl, Eva Maria; Müller, Dirk ...
Schizophrenia research,
04/2001, Letnik:
49, Številka:
1
Journal Article
Recenzirano
Functional abnormalities in the interhemispheric transfer via the corpus callosum in schizophrenia may result in filtering problems and information processing problems, which may in turn be related ...to the synchronization of cortical event-related activity. To explore whether a relationship exists between corpus callosum (CC) size, measured with in-vivo magnetic resonance imaging, and late auditory event-related P300 potentials, 50 patients with schizophrenia as well as 50 healthy controls were examined. The absolute CC size and subregional areas, as well as the CC areas adjusted for total brain volume, were not significantly different between patients with schizophrenia and controls. While no significant group differences were observed for P3a-, P3b-, PSW-amplitudes and P3b-latencies, P3a- and PSW-latencies were significantly prolonged for patients with schizophrenia. Absolute CC total size was significantly correlated with P3b-amplitudes in healthy controls (
r=0.29;
P=0.044). In patients with schizophrenia, significant correlations were observed between the subregion of the posterior body of the CC and positive slow wave (PSW;
r=0.47;
P=0.001). P3a-, P3b- and PSW-latencies were not significantly correlated to CC size in either patients with schizophrenia or healthy controls. The results are discussed in terms of the possibility that abnormalities in interhemispheric transfer may underlie the mechanisms of schizophrenia.
Olanzapine is a new atypical antipsychotic agent that belongs to the same chemical class as clozapine. The pharmacological efficacy of olanzapine (in contrast to that of risperidone) has been shown ...to be comparable to that of clozapine, but olanzapine has the advantage of producing a less pronounced bone marrow depressing effect than clozapine. The specific aims of this study were (a) to assess dopamine D^sub 2^/D^sub 3^ receptor availability in patients treated with olanzapine by means of iodine-123 iodobenzamide ^sup 123^IIBZM single-photon emission tomography (SPET), (b) to compare the results with findings of ^sup 123^IIBZM SPET in patients under treatment with risperidone and (c) to correlate the results with the occurrance of extrapyramidal side-effects (EPMS). Brain SPET scans were performed in 20 schizophrenic patients (DSM III R) at 2 h after i.v. administration of 185 MBq ^sup 123^IIBZM. Images were acquired using a triple-head gamma camera (Picker Prism 3000 XP). For semiquantitative evaluation of D^sub 2^/D^sub 3^ receptor binding, transverse slices corrected for attenuation were used to calculate specific uptake values STR-BKG/BKG (STR=striatum; BKG=background). The mean daily dose of olanzapine ranged from 0.05 to 0.6 mg/kg body weight. The dopamine D^sub 2^/D^sub 3^ receptor binding was reduced in all patients treated with olanzapine. Specific IBZM binding STR-BKG/BKG ranged from 0.13 to 0.61 (normal controls >0.95). The decreased D^sub 2^/D^sub 3^ receptor availability revealed an exponential dose-response relationship (r=-0.85, P<0.001). The slope of the curve was similar to that of risperidone and considerably higher than that of clozapine as compared with the results of a previously published study. EPMS were observed in only one patient, presenting with the lowest D^sub 2^/D^sub 3^ availability. The frequency of EPMS induced by olanzapine (5%) was considerably lower than the frequency under risperidone treatment (40%). Our findings suggest an exponential relationship between the daily dose of olanzapine striatal and decreased D^sub 2^/D^sub 3^ striatal binding availability. The results are consistent with the findings of in vitro experiments reporting a higher D^sub 2^/D^sub 3^ receptor affinity and a similar 5HT^sub 2^ receptor affinity of olanzapine as compared with clozapine. Thus, the decreased tendency to induce EPMS at therapeutic doses is not due to the limited occupancy of striatal D^sub 2^/D^sub 3^ receptors in vivo. Patients are protected from EPMS by other intrinsic effects of the drug, i.e. the combination of both D^sub 2^/D^sub 3^ and 5HT^sub 2^ receptor antagonism.PUBLICATION ABSTRACT
Event-related potentials (ERPs) can serve as markers for cognitive processing stages. Identification of those ERPs altered in schizophrenia offer information about cognitive dysfunction. Auditory ...evoked potentials (AEPs) were elicited within an oddball paradigm in 35 schizophrenic patients and compared with 35 healthy controls. N100 and P200, as well as N200, frontal P300 and parietal P300 subcomponents, were separated using dipole source analysis. The amplitudes of the N100 and the parietal P300 measured in schizophrenics were diminished. The input-related processing stages (N100 and P200) were not altered, whereas later, the deviant and task-related processes (N200, frontal P300, parietal P300 and reaction time) were significantly prolonged in schizophrenia.
Objectives. Schizophrenia is associated with replicable grey matter volume reductions in fronto-temporo-limbic and subcortical regions. Psychometric schizotypy refers to a set of behavioural traits ...and cognitions thought to represent the subclinical manifestation of schizophrenia in the general population. While there is evidence of a continuum between schizophrenia and schizotypy at phenotypic, genetic and cognitive levels, no previous study has observed grey matter volume reductions associated with increased psychometric schizotypy levels in healthy individuals. Such evidence would provide further support for a relationship between non-clinical schizophrenia-like traits in the general population and the full-blown clinical condition of schizophrenia. Methods. We used magnetic resonance imaging to investigate the relationship between psychometric schizotypy and brain structure in 55 clinically unaffected and unmedicated volunteers. We performed a voxel-based morphometry analysis of grey matter volume data obtained at 1.5 Tesla. Results. Covarying for age and gender, higher scores of self-report positive schizotypy were significantly associated with reduced grey matter volume in medial prefrontal, orbitofrontal, and temporal cortical regions. Conclusions. These findings show that psychometric schizotypy in healthy individuals is associated with volume reductions in cortical areas known to be altered in schizophrenia, thereby providing neurobiological evidence of a continuum between schizotypy and schizophrenia.
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