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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

20 postacute schizophrenic patients with predominantly negative symptoms and 21 age and sex matched normal controls were investigated in a P300 paradigm with simultaneous measurement of EP, EMG and behavioural reaction time. The steps of central information processing were operationalized by the following measures: input processing time (IPT): N1-latency; central processing time (CPT): N1-latency until EMG-onset; motor execution time (MET): EMG-onset until onset of target behaviour. For the schizophrenic group we found a pattern of significant deviations with reduction of the N1-, N2- and P3-amplitude, prolongation of the central processing, motor execution and behavioural termination time. The largest loss of time however was found for the central information processing time (203.1 +/- 72.9 vs. 113.1 vs. 20.2 ms, p = 0.000). In the control group the EMG reaction started 12.4 ms before the N2 peak, in the schizophrenic group 63.5 ms after the N2 peak (p = 0.02). Summing up, these findings are compatible with the assumption of a multiple functional deficit of central information processing in schizophrenia.
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PMID:[Analysis of reaction time in post-acute schizophrenia using electrophysiologic variables]. 876 92

Reduced P300 amplitude in schizophrenia has been a consistent finding. Recent studies have raised the question of characteristic topographic distribution. This study reports the effects of binaural and unilateral stimuli on the P300 topography in schizophrenia. An auditory "oddball" paradigm was repeated 3 times with left, right and binaural stimulation. Data were recorded using a 19-electrode montage with linked ear reference. Subjects were 18 untreated, hallucinating, paranoid patients with schizophrenia and 24 healthy matched volunteers. For the control subjects, stimulus conditions had no effect on P300 topography. For the sample with schizophrenia, topography under unilateral left stimulation resembled that of control subjects. Binaural and right-sided stimulation shifted peak amplitudes to the right and frontally. In addition to the usually observed parietal peak, a second P300 maximum having a different time course appeared over right frontal areas. The data provide further support for lateralized dysfunction in schizophrenia.
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PMID:The effect of laterality of stimulus presentation on auditory P300 topography in schizophrenia. 882 Jan 72

In this study the N400 of schizophrenics was compared with that of control subjects in a picture semantic-matching task. The comparison of N400 difference waveforms (subtraction of event-related potentials of congruent from those of incongruent trials) between control and patients was supplemented by separate analysis for congruent and incongruent trials. The N400 latency was delayed in patients. Also, the amplitude of N400 in the difference waveform was reduced in schizophrenics; however only congruent trials were different for patients (more negative) with respect to controls. This result is consistent with the hypothesis that schizophrenics use context poorly, but inconsistent with simple versions of the idea that associations are generally disinhibited in schizophrenia. Since the amplitudes of N400 and an auditory P300 were not correlated, a general processing deficit does not explain the results. Finally, by using picture matching, a cross-cultural comparison of N400 in schizophrenics from Cuba and China was possible, which indicated that the N400 abnormalities were similar in both groups.
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PMID:Semantic matching of pictures in schizophrenia: a cross-cultural ERP study. 883 Sep 52

This study examined whether abnormalities in event-related potentials (ERPs), reported in schizophrenia, extend to patients with schizotypal personality disorder (SPD). Auditory ERPs in an oddball paradigm were obtained in 19 SPD patients, 17 schizophrenic patients, and 20 normal control subjects (NCs). Schizophrenic patients had lower P300 amplitude than NCs; the P300 amplitude of SPD patients was intermediate, showing a linear trend but not a significant group difference. P200 amplitudes showed a similar trend. SPD patients had N100 and N200 amplitudes intermediate to schizophrenic patients and NCs, without significant group differences. Results suggest diminished P300 amplitude may not be as prominent in SPD as in schizophrenia. Studies with larger sample sizes, multiple lead assessment strategies, and more demanding tasks may further characterize ERP deficits in schizophrenia-spectrum disorders such as SPD.
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PMID:Event-related potentials in schizotypal personality disorder. 884 99

In large families with affective illness, identification of a biological variable is needed that reflects brain dysfunction at an earlier point than symptom development. Eye movement disorder, a possible vulnerability marker in schizophrenia, is less clearly associated with affective illness, although a subgroup of affective disorders shows smooth-pursuit eye movement disorder. The auditory P300 event-related potential may be a useful marker for risk to schizophrenia, but a role in bipolar illness is less certain. The distribution of these two biological variables and their association with symptoms in two multiply affected bipolar families is described. In a single, five-generation family identified for linkage studies through two bipolar I (BPI) probands, 128 members (including 20 spouses) were interviewed. The 108 related individuals had diagnoses of BPI (7), bipolar II (2), cyclothymia (3), or major depressive disorder (19). Eight others had generalised anxiety (1), minor depression (5), intermittent depression (1), or alcoholism (1). Sixty-nine subjects had no psychiatric diagnosis. P300 latency (81) and eye tracking (71) were recorded from a subgroup of relatives within the pedigree. Eye tracking was abnormal in 11 of 71 relatives (15.5%) and was bimodally distributed. In these 11 relatives, clinical diagnoses included minor depression (1), alcoholism (1) and generalised anxiety disorder (1). P300 latency was normally distributed and did not differ from controls. In a second family in which five of seven siblings have BPI illness, P300 latency and eye movement disorder were found in affected relatives and in some unaffected offspring. In these large families, clinical diagnoses of general anxiety, alcoholism and minor depression, when associated with eye tracking abnormality, may be considered alternative clinical manifestations of the same trait that in other relatives is expressed as bipolar illness.
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PMID:Implications of comorbidity for genetic studies of bipolar disorder: P300 and eye tracking as biological markers for illness. 886 53

Asymmetrical topography of the auditory P300 with reduced left hemispheric amplitudes and, consequently, a right-lateralized peak of the P300 electrical field has been repeatedly reported in schizophrenia. This was interpreted as an indication of reduced left-hemispheric activity during the simple cognitive P300 task. Since generator locations calculated from the surface potentials are ambiguous, further evidence is required to support this conclusion. In the present study, 13 stabilized DSM-III-R schizophrenic patients were studied with an auditory P300 paradigm and neuropsychological methods sensitive to functional brain asymmetries. The tests included the verbal paired associates test (Goldstein et al 1988, Cortex 24:41-52) and the nonspatial conditional associative learning test (Petrides 1985, Neuropsychologia 23:601-614). A significant correlation was found between right-sided lateralization of the P300 maximal positivity and neuropsychological evidence for left hemispheric temporal- hippocampal dysfunction. Attentional performance was correlated with P300 amplitudes. The results of this study provide further evidence that right-sided lateralization of the P300 peaks results from dysfunction of left-hemispheric neuronal generators.
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PMID:Auditory P300 topography and neuropsychological test performance: evidence for left hemispheric dysfunction in schizophrenia. 902 56

Auditory event-related potentials (ERPs) were obtained from 33 schizophrenics, from 16 families multiply affected with schizophrenia, 57 of their non-schizophrenic first-degree relatives and 32 unrelated healthy controls. Transmission of schizophrenia in these families appeared unilinear with one parent only transmitting the disorder. Consequently, we were able to identify 10 presumed obligate carriers and study eight of them. Schizophrenic patients showed latency prolongation and amplitude reduction of the N100, N200 and P300 waves compared to controls. Their relatives showed similar abnormalities compared to controls. There was a trend for bimodal distribution of the P300 latency in the relatives, with 20 (35%) of them falling outside two standard deviations of the mean of the controls. These included six of the eight obligate carriers. Our results suggest that ERP abnormalities may serve as markers of genetic vulnerability in schizophrenia and may be useful in genetic linkage studies.
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PMID:The Maudsley Family Study, II: Endogenous event-related potentials in familial schizophrenia. 905 Jan 27

In the past it was reported in several studies that both depressive and schizophrenic patients exhibit reduced P300 amplitudes compared to healthy controls. In order to elucidate the underlying mechanisms of spectral P300 generation, we analysed P300 responses in depression and schizophrenia by a frequency based approach. Herefore, the amplification (poststimulus/prestimulus) of spectral power in different frequency bands was evaluated for non-target and target epochs. Generally, we found that P300 responses are accompanied by a pronounced frequency amplification in the delta and theta range. For the depressive patients we detected only under target condition a statistically significant reduction of alpha and gamma amplification compared to controls. In contrast to this, we observed a highly significant reduction of delta amplification in schizophrenic patients, under both target and non-target conditions.
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PMID:Spectral analysis of P300 generation in depression and schizophrenia. 909 3

Evidence of abnormal auditory evoked potentials (EPs) in patients suffering from schizophrenia has been accumulating. In spite of the magnitude of the EPs in schizophrenia literature, EPs have not been found to be clinically useful thus far. In this study we attempted to replicate the findings in a large sample of schizophrenia patients, and describe how auditory EPs may be used as supplemental tests in the differential diagnostic process. Five subject groups were formed; paranoid (PAR) and disorganized/undifferentiated (disorg/undiff) schizophrenics, schizoaffective (SA), bipolar, and a normal control group. All patients were stable on medications. Subjects underwent one EP recording session. Classification and regression trees (CART) based on EP amplitudes were used to classify subjects into subgroups. The optimal Bayes classification rule that minimizes the expected misclassification cost was then constructed for various misclassification cost functions. In a standard 'Odd Ball' paradigm the N100 amplitudes were significantly decreased in the disorg/undiff group than in the bipolar or normal subjects. The P200 amplitude was smaller in the PAR, disorg/undiff and the SA groups than in the normal controls. Both the disorg/undiff and the PAR groups had significantly lower P300 amplitudes than the normal controls. Classification rules used to classify subjects into normal or ill were sensitive to the relative cost of misclassifying a subject, as well as the prior clinical probability that this subject was ill. Our data largely agree with the existing literature showing abnormally decreased N100, P200, and P300 amplitudes in schizophrenic patients, particularly the disorg/undiff patients. We conclude that whether EP measures are clinically useful depends on the clinical situation. In particular, the prior probability of the diagnosis in question being present and the cost of misclassifying the patient are critical.
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PMID:Auditory evoked potentials, clinical vs. research applications. 910 86

In order to address basic mechanisms behind a reduced averaged P300 wave in schizophrenia and depression, 17 unmedicated schizophrenic and 11 unmedicated depressive subjects were tested in an 'oddball paradigm' against healthy controls matched for gender and age. The amplitude distributions of single trials' maximum positive deflections after stimulation (P300) for both target and nontarget stimuli were determined, which served as a basis for calculating the discrimination index d'. This index characterizes differences in the electrophysiological responses to target and nontarget stimuli of a subject being engaged in a discrimination task. As a main result d' was significantly lower for schizophrenics than for their controls. Directly compared to depressive subjects, schizophrenics also depicted a statistically significant decrease of the discrimination index, which could not be explained by differences in age. Although the averaged P300 signals did not show any significant differences between the two diagnostic groups, the approach of calculating d' on the basis of single trial analysis differentiated between schizophrenics and depressives. In conclusion, schizophrenic patients revealed different functional features when generating event-related potentials in an 'oddball paradigm' compared to healthy controls and depressives.
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PMID:Differential pathophysiological mechanisms of reduced P300 amplitude in schizophrenia and depression: a single trial analysis. 926 77


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