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

Brain ERPs were recorded in ten unmedicated schizophrenic patients and age- and sex-matched healthy controls during a multidimensional listening task. Patients showed a marked reduction in a long-duration attention-related negative ERP component, termed 'processing negativity' (PN), which was elicited by attended stimuli. The amplitude of PN was significantly correlated with SANS and SAPS scores of schizophrenic symptoms. The P300 component was also reduced in amplitude in patients, and was significantly correlated with SANS ratings of negative thought disorder. These findings provide neurophysiological evidence of impairment in the maintenance of selective attention and the cognitive processes associated with target detection among schizophrenic patients. The reduced PN in schizophrenics implicates frontostriatal pathways in the aetiology of attentional deficits in schizophrenia.
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PMID:Auditory selective attention and event-related potentials in schizophrenia. 205 68

In a pilot study, the P300 component of the ERP subsequent to competitive visual stimulation was examined in 12 schizophrenic patients (paranoid hallucinatory schizophrenia in partial remission, neuroleptic medication). In the competitive stimulation with a varying information content of the non-target stimuli, healthy probands showed a distinct increase in the amplitude of the P300 components according to a in the frequency of the non-target stimuli. The P300 components during these changing stimulatory conditions remained constant in the schizophrenic patients. This reduction in the reactivity of the P300 component subsequent to an increasing information content of the non-target stimuli can be interpreted as a disturbance in the selective information processing. The ability to adequately react to the information content of irrelevant stimuli appears to be reduced in the schizophrenic patients we examined.
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PMID:The P300 component of event-related potentials in schizophrenic patients. 342 84

To replicate the findings of a sensory gating deficit in schizophrenia, and to determine if normals and schizophrenics are equally affected by cognitively mediated task-relevant factors, 10 healthy and 10 schizophrenic young adults were tested in two experimental conditions. In the first condition a pair of identical auditory clicks (conditioning stimulus and testing stimulus) was administered at an inter-stimulus interval fixed at 500 msec. In the second condition, the second stimulus could have one of two possible frequencies, and subjects were required to count the presentations of one and ignore the other. Subjects also completed two matched blocks of single stimulus (i.e. testing only) presentations to provide a baseline for assessing the effect of the warning stimulus on the evoked response. We found, in disagreement with previous results, that in schizophrenics, passive exposure to the paired stimuli produced a suppression of P50 amplitude to the second stimulus, that did not differ from that found in normals. However, under paired presentation conditions, testing P50 amplitude in normals, but not in schizophrenics, was enhanced by the count/no-count task introduction. We suggest that both groups are equally susceptible to the task independent (possibly "hard-wired") suppressing effect of a conditioning stimulus presentation. However, only normals seem to exhibit a task-dependent effect, whose action at the P50 range demands the presence of a warning (conditioning) stimulus. Inspection of the full epoch data showed an apparently lesser task-related, warning dependent modulation of early ERP activity in schizophrenics, and a normal (or even supernormal) modulation of late activity. We consider this to support a notion of an early processing deficit in schizophrenia.
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PMID:Sensory gating deviance in schizophrenia in the context of task related effects. 787 34

The present study was designed to determine the intercorrelation between schizophrenic symptoms, brain morphology, electrophysiological and neuropsychological variables. 44 patients, who met ICD-10 criteria for schizophrenic disorder, were included. At baseline, after 3 and 6 weeks BPRS, CGI, psychometric measurements and QEEG/ERP were performed. A CT scan was performed only at the beginning of the study. Data were evaluated by a multivariate test for data with an inherent structure. One of the most interesting findings is a correlation between BPRS total score and theta EEG power at baseline as well as under treatment. In conclusion, the study suggests the usefulness of multimethodological approaches in order to optimise diagnostic procedures in schizophrenia.
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PMID:[Intercorrelation of psychopathological, morphologic, neurophysiologic an psychometric parameters in schizophrenic patients]. 934 Mar 12

Bleuler and Kraepelin are described as icons of the aggressively psychological and aggressively biologic approaches to schizophrenia. We suggest that methodologic advances in studying the function and structure of the brain now allow a reconciliation of these seemingly dissimilar approaches, particularly in the temporal lobe. We begin with a brief historic overview of these different approaches to schizophrenia and then describe structural (magnetic resonance imaging [MRI]), functional (event-related potential [ERP]), and neuropsychological studies in this disorder, including a summary of work conducted in our own laboratory. Recent MRI investigations agree on the presence of volume reductions in schizophrenia in the medial temporal lobe structures of the hippocampus-amygdala complex and of the para-hippocampal gyrus. Furthermore, two recent studies also indicate volume reductions in the superior temporal gyrus (STG). These volume reductions are most prominent in male patients and in the left hemisphere of right-handed patients with schizophrenia. Along with structural studies, there has been a burgeoning interest in MRI-clinical correlations, with volume reductions in the anterior STG being associated with hallucinations and those in the posterior STG being associated with thought disorder. Functional ERP studies also implicate the importance of the temporal lobe in schizophrenia; in addition, ERP abnormalities have been directly associated with a left greater than right MRI volume reduction of the posterior STG. Neuropsychological studies in nonpsychiatric patients are also consistent with a pattern of functional deficits shown to arise from temporal lobe abnormalities, whereas direct MRI-neuropsychological correlations in schizophrenic patients show that decreased performance on tests of verbal memory, abstraction, and categorization correlates with reduced MRI volume of left and right temporal lobe structures. Integration of these findings with those from basic neuroscience suggests a possible role of excitatory amino acid neurotransmission dysregulation and excitotoxicity in the pathology of schizophrenia. A data-based pathophysiologic characterization of schizophrenia is now becoming a reality, and the next few years should see a further unification of the Kraepelinian and Bleulerian approaches to this disorder.
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PMID:Uniting Kraepelin and Bleuler: the psychology of schizophrenia and the biology of temporal lobe abnormalities. 938 26

Auditory P300 amplitude reductions are well-established in young adults with schizophrenia. Little is known, however, regarding the P300 in older schizophrenia patients, especially those with late onset. We studied 28 middle-aged and elderly (mean age = 62.7 years) patients [14 with early onset schizophrenia (EOS) and 14 with late onset schizophrenia (LOS)] and 14 normal comparison (NC) participants using an auditory oddball paradigm. Event-related potentials were recorded from 15 scalp electrodes and six non-scalp sites. There were no significant differences between EOS and LOS groups in neuroleptic dosage, symptom severity, reaction times, target-detection accuracy, or N100 and N200 ERP measures. The EOS, but not the LOS, group had significantly smaller auditory oddball P300 amplitudes than the NC group. Twelve of the 14 LOS patients had P300 amplitudes in the normal range. Smaller P300 amplitudes were associated with earlier age of onset (r = 0.48), longer duration of illness (r = -0.49) and more severe alogia (r = -0.50). We conclude that P300 abnormalities in schizophrenia may be a marker for a disease subtype with early onset and more severe information-processing deficits.
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PMID:Relationship between auditory P300 amplitude and age of onset of schizophrenia in older patients. 970 71

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

The existence of a genetic background is well admitted in schizophrenia, but some individuals at genetic risk for that disease could never manifest it at a clinical level. However, several vulnerability models could help us to identify such individuals. According to them, when similar perturbations at a given task are observed both in clinically stable patients with schizophrenia and their nonschizophrenic first degree relatives, this task could be qualify as an indicator of the vulnerability to schizophrenia. In literature, that seems the case for auditory ERP late components in oddball paradigms. Our study was undertaken to replicate literature data. For that purpose, amplitude and latencies of auditory N100, P200, N200 and P300 wave-forms were assessed among 21 clinically, stable schizophrenics, 21 of their biological full siblings and 21 unrelated control subjects matched with the two others groups for several socio-demographic factors. Comparison were performed by non parametric analyses (Kruskal-Wallis one way ANOVA, and post-hoc Mann-Whitney). Compared to controls, delayed latencies and/or reduced amplitudes were observed for several ERP components--mainly with P300--in the sibling group. ERP values from this group did not statistically differ from those of the group with schizophrenia. In conclusion, results from the sibling group suggest that ERP impairments in auditory oddball paradigms may actually represent indicators of the genetic vulnerability to schizophrenia.
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PMID:[Vulnerability to schizophrenia. II: Familial status of auditory evoked potential abnormalities]. 1054 83

Impairments of recognition memory for words and attenuation of the ERP 'old-new' effect have been found in patients with left medial temporal lobe damage. If left temporal lobe dysfunction in schizophrenia involves medial structures (e.g. hippocampus), then schizophrenic patients might show similar abnormalities of verbal recognition memory. This study recorded ERPs from 30 electrode sites while subjects were engaged in a continuous word recognition memory task. Results are reported for 24 patients having a diagnosis of schizophrenia (n = 16) or schizoaffective disorder (n = 8) and 19 age-matched healthy controls. Both patients and controls showed the expected 'old-new' effect, with greater late positivity to correctly recognized old words at posterior sites, and there was also no significant difference between groups in P3 amplitude. However, accuracy of word recognition memory was poorer in patients than controls, and patients showed markedly smaller N2 amplitude. Reduced amplitudes of N2 and N2-P3 were associated with poorer performance, with highest correlations over the left inferior parietal (N2) and left medial parietal (N2-P3) region. Moreover, patients failed to show significantly greater left than right hemisphere amplitude of N2-P3 at posterior sites, which was seen for healthy controls. These findings suggest that impaired word recognition in schizophrenia may arise from a left lateralized deficit at an early stage of processing, beginning at 200-300 ms after word onset.
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PMID:Brain event-related potentials (ERPs) in schizophrenia during a word recognition memory task. 1061 49

Previous studies have revealed various abnormalities in late-component ERP amplitude and latency in schizophrenia, considered as a diagnostic category. The aim of this study was to investigate the within-sample associations between late-component ERPs and three primary syndromes of schizophrenia Reality Distortion, Psychomotor Poverty and Disorganisation. Subjects included 40 schizophrenics and 40 age and sex matched nonpsychiatric controls. Auditory ERPs (N100, N200, P200, P300) were elicited using an auditory oddball paradigm. Between-group analyses of target data showed reduced N100, N200 and P300 amplitude, increased P200 amplitude and delayed N200 latency in schizophrenics compared to controls. For non-target data, schizophrenics showed similarly reduced N100 amplitude and delayed N200 latency. Within-group analyses of target data showed that the three syndromes (determined by principal component analysis of PANSS ratings) were differentiated by ERP latency, but not amplitude (Disorganisation delayed left hemisphere P200 and P300 latency; Reality Distortion earlier global, midline and left hemisphere N200 latency; Psychomotor Poverty delayed posterior N100 latency). Notably, only Disorganisation showed a divergent pattern of associations with non-target ERP data: reduced P200 amplitude and delayed N100 latency.
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PMID:Late component ERPs are associated with three syndromes in schizophrenia. 1106 45


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