Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There have been many reports on the Event-Related Potentials (ERPs) abnormalities, especially P300 amplitudes reduction, in schizophrenic patients. However the relationships between P300 abnormalities and schizophrenic subtypes have not been clarified. This study aims to investigate the relationships in a relatively large number of drug free schizophrenics. Seventy three unmedicated schizophrenic patients (45 males, 28 females) who met the DSM-III-R criteria for schizophrenia were tested. Twenty seven of the schizophrenics were paranoid type according to the DSM-III-R, 23 were undifferentiated, 19 were disorganized, 2 catatonic and 2 residual. Seventy three healthy controls were age and gender matched to the patient group. All the ERPs were recorded during auditory odd ball task. Stimuli consists of 2 kHz and 1 kHz tone bursts, and the respective probabilities of the rare and frequent stimuli were 0.2 and 0.8. They were presented random order. The duration of each stimulus was 90 msec with rise and fall times of 10 msec, and the intensity was approximately 70 dB SPL for all the stimuli. The inter-stimulus intervals were 1.7 +/- 0.1 seconds. The subjects were instructed to count the numbers of rare tones. The scalp EEGs were recorded from Ag-AgCl electrodes at 16 sites that referred to linked earlobes. P300 amplitudes reduction [F (1,144) = 39.33, p < 0.001] and P300 latencies prolongation [F (1,144) = 12.41, p < 0.001] were found in schizophrenic group as a whole. Lower amplitude of P300 was observed at both right and left temporal sites in the subjects with undifferentiated type and disorganized type. Although in the subjects with paranoid type, the reduction was recognized at left temporal region, reduced amplitude was not seen at right temporal site. While no relationships between P300 amplitudes, the score of BPRS and SAPS were detected, in the patient with paranoid type, significant negative correlation between P300 amplitudes and SANS total scores was observed (r = -0.425, p = 0.03) at Pz site. These results were discussed with respect to cognitive impairment of schizophrenia.
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PMID:[Cognitive impairment in schizophrenic patients on event-related potentials component P300]. 837 57

The authors reviewed the literature on evoked potentials in mentally ill patients, with particular emphasis on schizphreniacs. The commonly observed abnormalities were as follows: 1) higher SEPs amplitudes with less waveshape variability during first 100 ms in non-depressed chronic, paranoid or undifferentiated patients with florid psychotic symptoms; normal SEPs amplitudes in acute or latent schizophrenics and in chronic depressed schizophrenics but without florid psychotic symptoms; 2) reduced SEPs and VEPs amplitude recovery and faster latency recovery; 3) reduced AEPs amplitude and latency; 4) greater VEPs waveshape variability and tendency to be "reducers" in hallucinating patients; reduced amplitude and latency recovery; prolonged latencies in patients with positive family history (schizophrenia or affective disorders in close relatives); prolonged N2 latency in motor responses to "easy" and "difficult" stimuli; reduced activity of "late potentials"; 5) greater waveshape variability in all modalities in chronic schizophrenics, abnormal P300 (reduced amplitude, lack of P300 or negative "effect of uncertainty") and abnormal CNV (less "readiness" potential, prolonged negativity with motor responses).
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PMID:[Brain evoked potential in schizophrenic patients]. 841 1

Abnormalities in the auditory P300 event-related potential are one of the most robust findings in schizophrenia. To investigate the brain source(s) of this major functional abnormality, we combined P300 recordings with the use of a new generation of magnetic resonance imaging (MRI) technology to examine specific temporal lobe gray matter regions of interest in schizophrenics and normal controls. In schizophrenics, gray matter volume reductions in the left posterior superior temporal gyrus (STG), which includes Heschl's gyrus and the planum temporale, were highly and specifically associated with both P300 amplitude reduction and left < right topographic asymmetry. In contrast, left hippocampus and parahippocampal gyrus gray matter volume reductions, although present in schizophrenics, were not associated with any P300 abnormalities. There were also no statistically significant correlations between P300 amplitude at any of the central or left-sided electrode sites or any of the MRI-defined volumes of gray matter regions of interest in the right temporal lobe, superior frontal gyrus, or cingulate gyrus; additional work will thus be required to determine the role of these regions, if any, in P300 generation, along with the role of other brain areas not examined in the present study. These initial data appear most compatible with a model that postulates a major role for bilateral STG sources in P300 generation: The strongly asymmetric STG volume reduction (left < < right STG volume) found in many schizophrenic subjects produces asymmetric P300 amplitudes (left < < right) at lateral electrode sites, where the influence of the abnormal region is most easily detected.
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PMID:Auditory P300 abnormalities and left posterior superior temporal gyrus volume reduction in schizophrenia. 843 39

Loosening of thinking as assessed by the Object Sorting Test (OST) has been found in a percentage of normal subjects but in a higher percentage of schizophrenics, and is familially transmitted in both groups. Loosening of thinking in normal subjects is not associated with evidence of impaired function or increased psychopathology, and in recognition of this, it was termed allusive thinking rather than thought disorder. Both OST-assessed loosening and concreteness of thinking were found to be present independently in a high percentage of schizophrenics, so that both were considered to contribute to schizophrenic thought disorder. The presence of OST-assessed loosening in schizophrenics would, therefore, be predicted to correlate partially rather than totally with measures of schizophrenic thought disorder. It has been suggested that OST-assessed loosening in normal subjects is due to a genetically determined reduction in strength of an inhibitory process that limits the spread of activation of semantic associations and results in a predisposition to schizophrenia. The brain event-related potential P300, which is, in part, under genetic control, may index this inhibitory process. Therefore, it was predicted that in normal subjects, P300 would correlate with OST-assessed loosening of associations. If schizophrenic thought disorder is due to a further weakening of this inhibitory process, it can be predicted that P300 in schizophrenics correlates only weakly with OST-assessed loosening of thinking, but more strongly with schizophrenic thought disorder. In a study in which P300 was elicited using a difficult selective attention task with 15 unmedicated schizophrenics and 22 healthy subjects, all three predictions were supported.
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PMID:P300 indexes thought disorder in schizophrenics, but allusive thinking in normal subjects. 844 76

Abnormalities of auditory information processing represent a core feature of schizophrenic psychopathology. Event-related potentials (ERP) provide an objective index of the information processing deficits associated with schizophrenia and a tool for investigation of the underlying pathophysiology. The best established abnormality is a decrease in the amplitude of auditory P300. In an "oddball" paradigm, P300 is preceded by a series of earlier, negative-polarity ERP components that index discrete, prior information-processing events. The earliest such component, mismatch negativity (MMN), is elicited whenever a deviant, "oddball" stimulus interrupts a sequence of repetitive standard stimuli. MMN is generated principally within primary auditory cortex or adjacent structures on the superior temporal plane, suggesting that it indexes the earliest cortical event in the cognitive processing of auditory information. In the present study, MMN was studied in a group of 14 chronic schizophrenic subjects relative to 12 age- and IQ-matched normal controls in a passive auditory oddball paradigm in order to test the hypothesis that auditory information processing is impaired in schizophrenia, even at the level of primary sensory cortex. Schizophrenic subjects showed a significant reduction in MMN amplitude relative to controls, with a trend toward a greater deficit on the left than the right side. The finding of impaired MMN generation in schizophrenia suggests that information processing is impaired even at the level of auditory cortex and that the pathophysiological processes underlying information processing dysfunction in schizophrenia are widespread throughout the cortex, rather than limited to high-order association cortex such as prefrontal or mesial temporal cortex.
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PMID:Impairment of early cortical processing in schizophrenia: an event-related potential confirmation study. 851 35

The parameters of auditory P300 were studied with reference-independent methods in a group of 18 remitted and residual schizophrenics, and in 18 age- and sex-matched controls. In the schizophrenic group, significant inverse correlations were found between P300 amplitudes and level of psychopathology assessed with the Scale for Assessment of Negative Symptoms and with the Brief Psychiatric Rating Scale. Clinical variables regarding social functioning and adaptation, assessed with the Schedule for Affective Disorders and Schizophrenia, and with axis V of DSM-III-R, correlated significantly with low amplitudes. The scalp locations of the maxima and minima of the P300 potentials had the tendency to be dislocated to the right in schizophrenics compared with controls. The results indicate low P300 amplitudes to be associated with pervasive cognitive impairment. Future studies will determine whether low P300 amplitudes have prognostic validity for course and outcome of schizophrenic disorders.
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PMID:Amplitudes of auditory P300 in remitted and residual schizophrenics: correlations with clinical features. 851 25

Chronically activated macrophages and T-lymphocytes, along with excessive interleukin-2 and other cytokine secretions, were previously proposed as the fundamental mediators of schizophrenia. This paper provides further support for the immune model of schizophrenia, including evidence on neurotransmitter abnormalities, the low amplitude of the auditory P300 event-related potential, the neurodevelopmental model of schizophrenia and the possible involvement of the locus ceruleus in schizophrenia.
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PMID:The macrophage-T-lymphocyte theory of schizophrenia: additional evidence. 853 36

The P300 event-related potential (ERP) was recorded using the auditory oddball paradigm in 12 (6 male) schizophrenic (DSM-IIIR) patients in rigorously defined clinical remission. The ERP was also recorded in 10 (5 male) age-, sex- and education-matched control subjects. ERP latencies and amplitude were measured at Cz and Pz recording sites. Mean latencies of the P300 in schizophrenic patients in remission at Cz [343.6 +/- 31 (SD) ms] and Pz (346.15 +/- 30 ms) did not differ from those of normals (Cz: 332.8 +/- 23 ms, Pz: 323 +/- 38 ms). The P300 ERP amplitude was significantly (p < 0.05) smaller in schizophrenics in remission at both Cz (9.2 +/- 4.4 microV) and Pz (8.8 +/- 4.4 microV) than in normals (Cz: 13.3 +/- 2.90 microV; Pz: 12.71 +/- 4.18 microV). The significance of the smaller auditory P300 amplitude in schizophrenia is discussed.
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PMID:Smaller auditory P300 amplitude in schizophrenics in remission. 877 48

Distractibility and temporal modulation of attention in schizophrenics were studied using a visual reaction time task with additional auditory probe stimuli during the forewarning period or between trials. The probes were thought to exert a distracting influence, especially on schizophrenics, and at the same time they generated auditory EPs which allowed to track the modulation of cortical excitability during response preparation. The midline distribution of the terminal contingent negative variation (tCNV) and the amplitude of the postimperative negative variation (PINV) were clearly different in 20 DSM III-R schizophrenics, as compared with 20 alcoholics and 20 normal controls. In schizophrenics, the more frontal distribution of the tCNV was associated with a higher degree of psychopathology (measured with the Brief Psychiatric Rating Scale) and with delayed reactions. Probes between trials reduced tCNV and PINV in all subjects alike. However, this effect could not be attributed to distraction, because reaction times were faster in these trials, possibly due to an alerting effect of the auditory probes. The N100 and P300 amplitudes to probes in the forewarning period, i.e., during the negative potential shift of the CNV, were significantly enhanced in all groups. Apparently there is a state of increased cortical excitability during the CNV which is not selectively "tuned" toward relevant stimuli. In schizophrenia, the temporal and topographical regulation of this excitability is disturbed.
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PMID:CNV, PINV and probe-evoked potentials in schizophrenics. 859 73

P300 (P3) is a long-latency cognitive event-related potential (ERP) elicited by relevant target stimuli. P3 was recorded from 11 schizophrenics and 13 normal controls during a cued visual continuous performance task (CPT-AX). Cue-target sequences were presented at short and long interstimulus intervals (ISIs), in order to investigate working memory in schizophrenia. There was no significant between-group difference in P3 amplitude to validly or invalidly cued targets at short ISI. In contrast, P3 amplitude to invalidly cued targets at long ISI was significantly greater in schizophrenics than in controls, suggesting decreased ability to encode or maintain inhibitory representations of stimulus context. P3 amplitude is typically reduced in schizophrenic subjects in the auditory modality, and normal or reduced in the visual modality. This study, which demonstrates a paradoxical P3 increase to targets at long ISI, suggests that P3 impairment in schizophrenia cannot be attributed solely to structural deficits within P3-generator regions.
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PMID:Premature disinhibition of P3 generation in schizophrenia. 873 59


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