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

Evidence is growing that schizophrenic patients show significant structural damage in the temporal lobe limbic system. We review event-related potentials abnormalities (ERPs) in schizophrenia that may be related to dysfunction in this brain region or its inputs; ERPs discussed include the N100/P200, P300 and N400 components. Additional CT and clinical data have led our laboratory to a unifying working hypothesis of the presence of temporal lobe damage in schizophrenics that is evinced electrophysiologically as ERP alterations, structurally as tissue loss/derangement, and clinically as positive symptoms. The final section of this paper presents a new model of at least one form of schizophrenic pathology that, while speculative, incorporates experimentally based data from both our ERP work and from basic cellular physiology and pharmacology. The model proposes that positive symptoms of schizophrenia are related to limbic system pathology and in particular to a dysregulation of the NMDA form of excitatory amino acid transmission, potentiated by stress, and leading to cell damage and death due to 'excitotoxicity'.
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PMID:Event-related potentials in schizophrenia: their biological and clinical correlates and a new model of schizophrenic pathophysiology. 203 62

Variations in evoked potentials utilizing a photic stimulus in a sample of psychiatric patients compared to a healthy sample were evaluated. A group of patients diagnosed as schizophrenic was tested against a sample of healthy volunteers in a trial combining visual evoked potentials and a simultaneous cognitive processing. The stimulus was a checkerboard pattern presented under three different conditions. The results indicate diminished P100 and lack the reactivity associated with cognitive processes in schizophrenic group. The P200 component also lacked, in the inpatient group the changes associated with the performance of the trial. Finally the multiple P300 component was shortened in latency and decreased in amplitude in the schizophrenia group. Besides, P300 interhemispheric shifts related to trials, were commonly inverted in schizophrenics. Results are interpreted as a lacked interhemispheric coordination in schizophrenics, rather than a fixed hemispheric alteration. Likewise, an attenuation in processing from specific cortical areas to association cortex is concluded.
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PMID:Visual evoked potentials in a sample of schizophrenic patients. 229 77

Previous studies of schizophrenic patients have found evoked potential (EP) correlates of clinical symptomatology, including EP differences between subtypes of schizophrenia. In the current study, 14 medicated male schizophrenics underwent flash visual evoked potentials (VEP) and were clinically rated for positive and negative symptoms. We tested the hypothesis that positive symptoms would be associated with VEP latency reduction and negative symptoms with latency prolongation. Patients were divided into predominantly positive symptom and predominantly negative symptom groups using a combination of positive and negative symptom ratings. Patients with predominantly positive symptoms exhibited reduced latencies when compared with predominantly negative symptom patients. Similarly, significant negative correlations between positive symptom ratings and P200 latency variables were found. Correlations between negative symptom measures and P200 latencies (in the opposite direction) were also noted, but were less significant. These relationships persisted when confounders were statistically controlled for. The results are consistent with previous findings of evoked potential correlates of clinical symptomatology, especially those finding EP latency correlates of psychosis severity and affective blunting. The findings are discussed in relationship to concepts relevant to psychosis, including arousal, sensory gating, and the dopamine hypothesis.
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PMID:Visual evoked potential correlates of positive/negative symptoms in schizophrenia. 231 Jul 95

A number of studies using nontopographic analyses have reported an amplitude decrement of the auditory P200 component in schizophrenics compared to normal controls. Here we report a topographic analysis of the auditory P200 (204-272 ms; peak to baseline) in chronic medicated schizophrenics (N = 11) and normal controls (N = 18) and the correlation between this measure and clinical symptoms in schizophrenia. Exploratory T-statistic mapping (SPM) and "protected" Hotelling's T-squared contrasts of integrated voltages over the entire scalp showed that schizophrenics' P200 component had diminished amplitude in the left temporo-central region. Furthermore, P200 amplitude in the same scalp region during the experimental condition of counting infrequent tones was highly correlated with negative symptoms in the schizophrenic group.
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PMID:Clinical correlations of auditory P200 topography and left temporo-central deficits in schizophrenia: a preliminary study. 275 26

In 32 patients with major depressive disorders according to Research Diagnostic Criteria (RDC), symptomatology was rated using the Schedule for Affective Disorders and Schizophrenia (SADS), and somatosensory evoked potentials (SEP) elicited by tactile fingertip stimuli were recorded at the vertex of the scalp. Patients were drug-free except for benzodiazepines. Amplitudes and amplitude/stimulus intensity slopes were adjusted to same sex, age, height, and weight. Uni-and multivariate correlations revealed associations between the N140-P200 amplitude and hypothyroidlike aspects of depression with symptoms such as poor appetite and indecisiveness, and between the P100-N140 slope and intrapunitive aspects of depression with symptoms such as negative self-evaluation and suicidal attempts. Neither attention level nor benzodiazepine medication were reflected in these relationships.
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PMID:Depression and somatosensory evoked potentials: II. Correlations between SEP and depressive phenomenology. 613 58

Event-related potentials (ERPs) were examined in 16 college students who had high scores on the Schizophrenia Scale of the MMPI (HSS) but were without a hereditary disposition for major psychiatric disorders. 32 sex- and age-matched college students were used as controls. Subjects whose T scores were higher than 70 were designated the HSS subjects. ERPs were recorded during an auditory oddball task. Although neither the P300 latencies nor the P200 latencies differed between the two subject groups, the amplitudes of P300 to rare stimuli and P200 to frequent stimuli were lower in the HSS subjects than in the controls. These results suggest that deficits, both in the P300-related cognitive function to rare relevant stimuli, as well as matching and/or the comparison process for irrelevant frequent stimuli, may be present in HSS subjects. The HSS subjects, especially those with a combination of P300 and P200 deficits, even though without a hereditary diathesis for schizophrenia, may constitute one type of high-risk group.
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PMID:Deviate P200 and P300 in non-patient college students with high scores on the schizophrenia scale of the Minnesota Multiphasic Personality Inventory (MMPI). 820 8

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

Language disturbance in schizophrenia has been recently attributed to disturbed priming mechanisms. In the present study, event-related potentials (ERPs), were recorded to final words in sentences presented to 13 chronic patients with schizophrenia and 12 normal controls. Half of the final words fit a sentence context and another half did not. The N400 (the ERP sensitive to language) latency was prolonged, and its amplitude was more negative to both correct and incorrect sentence endings in the group with schizophrenia relative to the group of normal controls. The early ERP components, N100 and P200, were similar in both groups. These results suggest that language abnormalities in schizophrenia are related to a dysfunction in the language system and not to a general cognitive dysfunction, and may be related to poor use of context in patients with schizophrenia.
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PMID:ERP assessment of visual and auditory language processing in schizophrenia. 910 20

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

A number of studies have examined across-trial averaged late component. Event Related Potentials (EPR) and Reaction Times (RT) in response to multiple target stimuli. In this study, within-trial relatively fast and slow sub averages are additionally examined, in 20 patients with schizophrenia and 20 age and sex matched controls. A conventional auditory oddball paradigm. Across-trial ERP average analysis showed smaller N200 amplitude and delayed latency (but larger P200 amplitude) in patients with schizophrenia compared with controls. Within-trial ERP analysis revealed a number of additional findings. Controls showed distinctive differences in fast compared with slow ERP sub averages (smaller P200 amplitude, increased N200/P300 amplitudes and earlier latencies). The schizophrenic group on the other hand, showed relatively similar fast versus slow subaverages (no differences in P200 amplitude and N200 latency). In addition, between-group (within-trial) analyses highlighted significant differences in earlier stages of processing (compared with across-trial averages) in both fast and slow subaverages (increased N100 amplitude in controls). The complementary within-trial (compared with across-trial) data are interpreted with respect to a possible disturbance in inhibitory function in patients with schizophrenia.
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PMID:Fast and slow reaction times and associated ERPs in patients with schizophrenia and controls. 977 36


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