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)

Dopamine agonists impair and antagonists normalize prepulse inhibition (PPI) of startle and gating of the P50 event-related potential (ERP), but the within-subject effect of treatment on impaired gating in schizophrenia has not been studied. We report the first results of a longitudinal study using PPI of ERPs as a measure of sensory gating in an auditory Go/NoGo discrimination. After admission and approximately 3 months later, at discharge, 15 patients with schizophrenia performed a discrimination between a 1.4 kHz target tone and an 0.8 kHz non-target tone with no prepulse, or with a prepulse at 100 ms or 500 ms before either tone. ERPs were recorded from 19 sites. Healthy subjects were studied twice, with 3 months between sessions. PPI of the P50 peak in the 100-ms condition was reduced in patients on admission. At discharge, decreased negative symptoms correlated with enhanced P50-PPI at frontocentral sites. After treatment increased N100-PPI at centrotemporal sites correlated with fewer positive symptoms. At frontal sites in the 100-ms condition, the initially small difference of non-target minus target P300 amplitudes increased as negative symptoms decreased. It is concluded that weak auditory prepulses interfere with early auditory stimulus processing (P50), channel selection (N100) and selective attention (P300). Gating of these stages of processing is impaired in psychotic patients and treatment tends to normalize gating in tandem with improvements of different types of symptoms.
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PMID:A topographic event-related potential follow-up study on 'prepulse inhibition' in first and second episode patients with schizophrenia. 1032 Feb 10

Event-related potentials (ERPs) provide a noninvasive method to evaluate neural activation and cognitive processes in schizophrenia. The pathophysiological significance of these findings would be greatly enhanced if scalp-recorded ERP abnormalities could be related to specific neural circuits and/or regions of the brain. Using quantitative approaches in which scalp-recorded ERP components are correlated with underlying neuroanatomy in schizophrenia, we focused on biophysical and statistical procedures (partial least squares) to relate the auditory P300 component to anatomic measures obtained from quantitative magnetic resonance imaging. These findings are consistent with other evidence that temporal lobe structures contribute to the generation of the scalp-recorded P300 component and that P300 amplitude asymmetry over temporal recording sites on the scalp may reflect anatomic asymmetries in the volume of the superior temporal gyrus in schizophrenia.
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PMID:Identification of neural circuits underlying P300 abnormalities in schizophrenia. 1035 63

Noises elicit startle blinks that are inhibited when immediately (approximately 100 ms) preceded by non-startling prepulses, perhaps reflecting automatic sensory gating. Startle blinks are facilitated when preceded by prepulses at longer lead intervals, perhaps reflecting strategic processes. Event-related brain potentials (ERPs) and startle blinks were used to investigate the well-documented prepulse inhibition failure in schizophrenia. Blinks and ERPs were recorded from 15 schizophrenic men and 20 age-matched controls to noises alone and to noises preceded by prepulses at 120 (PP120), 500 (PP500) and 4000 ms (PP4000) lead intervals. Neither blinks nor any of the ERP components elicited by the noise alone differentiated schizophrenics from controls, although responses to noises were modified by prepulses differently in the two groups. With the N1 component of the ERP, patients showed normal inhibition but lacked facilitation, and with P2, patients lacked inhibition, but showed normal facilitation. With reflex blinks and P300, inhibition was seen in both groups, but no facilitation. These results suggest that different neural circuits are involved in blink and cortical reflections of startle modification in schizophrenics and controls, with both automatic and strategic processes being impaired in schizophrenia.
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PMID:Failures of automatic and strategic processing in schizophrenia: comparisons of event-related brain potential and startle blink modification. 1037 50

P300 amplitude reduction and P300 latency prolongation are consistent findings in schizophrenia, but it is unclear if these abnormalities were the effect of current or past neuroleptic treatment or were present at the onset of illness. We previously recorded ERPs in drug free schizophrenic patients (45 neuroleptic-naive and 56 previously treated with neuroleptics). In that study, P300 amplitude reduction was observed in both the neuroleptic-naive and the previously treated patients. However, both N200 and P300 latencies were prolonged only in the previously treated schizophrenic patients. In this study, we investigated ERPs in 60 drug free schizophrenic patients before and after neuroleptic treatment was begun. According to DSM-IV, schizophrenia subtype classification, 26 cases were paranoid type, 14 were disorganized, 2 catatonic and 18 undifferentiated. Twenty six of the patients were neuroleptic-naive and 34 had been previously treated. Sixty gender- and age-matched healthy controls were also investigated. ERPs were recorded during an auditory oddball task. The scalp EEGs were recorded from AgAgCl electrodes at 16 sites according to the international 10-20 system. Clinical symptoms were assessed using the Brief Psychiatric Rating Scale (BPRS). Before treatment, all schizophrenic patients displayed larger N200 amplitudes than the controls; however, increases in N200 amplitudes were not observed after neuroleptic treatment was begun. Both N200 and P300 latencies in the patients before treatment were prolonged only in those previously treated. Neuroleptic-naive patients demonstrated prolongation of both N200 and P300 latencies only after treatment. P300 amplitudes in patients were increased by neuroleptic treatment; but patients had smaller P300 amplitudes than the controls even after treatment. The change in P300 amplitudes (Pz) and the change in total BPRS scores by neuroleptic treatment were positively correlated in the patients whose duration of illness was six months or less (mean: 2.4 months). However, no correlation was observed for patients whose duration of illness was over six months (mean: 49.7 months). There were no significant differences in ERPs changes among subtypes. These results suggested that the P300 amplitude should be considered a vulnerability marker in schizophrenia and that both N200 and P300 latencies might be markers for neuroleptic exposure.
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PMID:[ERPs changes during neuroleptic treatment in schizophrenia--a vulnerability marker in schizophrenia]. 1037 77

1. The relationship between the P300 component of event-related potentials and disability of daily life was examined in schizophrenia. The subjects were 26 chronic schizophrenic patients. 2. Disability of daily life was assessed by using the Life Assessment Scale for Mental Illness (LASMI). 3. Auditory event-related potentials were recorded during a standard oddball task. 3. P300 amplitude correlated negatively with general psychopathology scale of PANSS (r = -0.416) and Work of LASMI (r = -0.417). P300 latency did not correlate with any of PANSS or LASMI score. 4. These results indicate that P300 amplitude can be an index for disability of daily life in schizophrenia.
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PMID:P300 and disability of daily life in schizophrenia. 1037 27

Recent studies of cerebral pathology in patients with schizophrenia have focused on symptomatological and electrophysiological correlates of reduced temporal lobe structure volumes. Volume deficits of the left superior temporal gyrus have been correlated with auditory hallucinations as well as to left-sided P300 amplitude reduction. However, caution is needed to interpret correlational data as evidence of a specific relationship. Therefore, a controlled study was undertaken on schizophrenic patients with and without auditory hallucinations. MRI-defined volumes of the left superior temporal gyrus and other temporal lobe structures were quantified from 3-mm coronal slices in 15 schizophrenic patients with chronic auditory hallucinations (hallucinators), 15 schizophrenic patients without auditory hallucinations (nonhallucinators) and 17 healthy controls. In all subjects a simple oddball paradigm was used to elicit P300 responses at temporal and centro-parietal electrode sites. No evidence was found for volume reductions of temporal lobe structures in the combined patient group compared with controls, or in the hallucinators compared with the nonhallucinators. The patients did show left P300 amplitude reduction compared with controls, particularly in the hallucinator group. Correlations between volumes of left temporal lobe structures and left P300 amplitudes were low and not significant. The results of the present study do not indicate that auditory hallucinations and associated abnormal electrophysiological activity are the consequence of atrophy of localized temporal lobe structures. However, replication in a larger sample of subjects is needed before firm conclusions can be drawn.
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PMID:A controlled study of temporal lobe structure volumes and P300 responses in schizophrenic patients with persistent auditory hallucinations. 1046 60

Awareness of illness is a crucial factor in schizophrenia, both for clinical management and psychopathological modeling. To date, there has been relatively little investigation of the influence of treatment with conventional versus atypical neuroleptics in relation to awareness and cognitive functions. The effect of clozapine treatment, compared with conventional neuroleptics, was studied in 22 schizophrenic patients in a crossover study. The P300 component of the event-related potential and scores on the Scale for Unawareness of Mental Disorder (SUMD), the Extrapyramidal Side Effects Scale (EPS), and Andreasen's Scales for the Assessment of Positive (SAPS) and Negative Symptoms (SANS) were studied at time 1 (conventional neuroleptic treatment) and time 2 (after 6 months of treatment with clozapine, in patients who interrupted the previous conventional regimen). Significantly increased P300 amplitudes were associated with clozapine treatment, together with heightened insight and reduced involuntary movements. The results confirm the effectiveness of clozapine not only in enhancing neurocognitive function, but also in increasing awareness of illness in schizophrenic patients.
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PMID:Effects of clozapine on awareness of illness and cognition in schizophrenia. 1048 43

Among the reasons for the relatively limited number of investigations of self-knowledge phenomena should be included, in addition to theoretical motives, the difficulties regarding the use of instruments available for this kind of approach and their content validity. This study investigates the relationship between subjective and objective deficits in schizophrenia, taking into account subjective experiences of cognitive impairment, clinical symptoms, and cognitive evoked potentials (P300 component). A group of 36 young schizophrenic patients (29 on neuroleptic treatment and seven drug-naive) were considered, together with a comparison group of 36 healthy subjects. Auditory event-correlated potentials (ERPs) were obtained using a simple "oddball" paradigm. Clinical symptoms were rated with the Brief Psychiatric Rating Scale (BPRS) and Scales for the Assessment of Positive and Negative Symptoms (SAPS and SANS), and while subjective disturbances were assessed by the Frankfurter Beschwerde Fragebogen (FBF, also called the Complaint Questionnaire). Correlation analysis showed that P300 amplitude was inversely correlated with subjective experiences of cognitive deficit, especially in the area of automatic skills and overstimulation. No relationship emerged between BPRS, SANS, and SAPS scores and P300 alterations. The results suggest that subjective cognitive disturbances, more than objective symptoms, are related to P300 alterations in schizophrenia, and that the FBF questionnaire appropriately covers the domain of schizophrenic cognitive disorders.
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PMID:Basic symptoms and P300 abnormalities in young schizophrenic patients. 1050 19

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

Many of the social, economic, and political problems facing people with schizophrenia are due to a misconception in the community that schizophrenia is not a biologically based disease but a myth. Because the diagnosis is based on self-reported symptoms, it is difficult for many people to acknowledge that schizophrenia is real. One goal of psychophysiological research has been to anchor both diagnosis and symptoms in biological reality. Reduction of the amplitude of the P300 component of the event-related potential (ERP) is the most replicable biological marker of the disease. Data are presented suggesting that P300 is both a state and a trait marker of the disease and may be sensitive to the progressive/degenerative course of the disease. Although the P300 tracks changes in clinical symptoms, it remains reduced even in patients in relative remission. P300 amplitude reduction is related to enduring negative symptoms, waning of attention, and gray matter volume deficits. ERP components other than P300 can also manifest the biological reality of various symptoms of the disease.
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PMID:Schizophrenia: the broken P300 and beyond. 1055 81


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