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

Evidence of hemispheric asymmetries in schizophrenia has been reported from different research areas. Asymmetries in evoked potential P300 topography are still controversial because of inconsistent findings. In the present study, previous results of abnormal lateralization of P300 were replicated in stabilized residual schizophrenic patients. Auditory P300 was recorded during an oddball task in which subjects detected rare target stimuli. Schizophrenic patients had the P300 peak shifted to the right hemisphere and differed significantly from age- and sex-matched normal control subjects who had left-lateralized P300 peaks. A comparison of different methods of assessment and analysis of the topographical features of the P300 electric fields showed that the extraction of reference-independent descriptors of P300 topography is a reliable and sensitive method for statistical handling of the maps. The results suggest left hemispheric dysfunction during cognitive tasks in a subgroup of schizophrenic patients. Inconsistencies between previous studies are likely to be due to heterogeneous patient groups, which may have included patients in an acute schizophrenic episode or patients in clinical remission. Investigation of the clinical meaning of P300 alterations requires careful psychopathological definition of the patient groups.
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PMID:P300 asymmetries in schizophrenia revisited with reference-independent methods. 787 Aug 55

Patients with schizophrenia appear to have abnormalities in both brain structures and information processing. Several recent reports have suggested that correlations exist between such measures. We examined the volume of several brain regions using magnetic resonance imaging (MRI), and also assessed both information processing, using brain event-related potentials (ERPs), and clinical symptomatology in sixteen medicated patients with schizophrenia. Subjects were tested using auditory and visual discrimination tasks. From the ERPs elicited by stimuli presented with relative probabilities of 0.1, the N100, N200, and P300 components were identified and measured. All subjects also had MRI scans that included 12 contiguous coronal sections, each 1 cm thick. From these scans, the following structures were identified and the volume or area quantified: third ventricle, lateral ventricles (partial), amygdala and hippocampus (one slice), partial brain volume (in one slice through the parietal lobe), and total prefrontal and temporal lobe gray and white matter in both cortical regions. Significant correlations were found between hippocampal area and the amplitude of the auditory and visual N200, and between the right hippocampus and the visual P300. Lower but significant correlations were seen between auditory P300 and measures of left temporal lobe structures. Auditory P300 amplitude correlated inversely with positive symptoms of schizophrenia. These preliminary results suggest that the ERP abnormalities in patients with schizophrenia are associated with temporal lobe pathology.
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PMID:Event-related potential abnormalities correlate with structural brain alterations and clinical features in patients with chronic schizophrenia. 791 Jul 55

The auditory P300 response and smooth pursuit eye tracking were recorded from a group of 23 male adult subjects who had been diagnosed in childhood as having schizoid personality. No differences were found in these physiological measures between the study group, their matched controls of other child psychiatric patients, and a group of population controls. The essentially negative findings are discussed in the light of abnormalities of these psychophysiological responses previously found in schizophrenic patients, in some of their biological relatives, and in other groups of psychiatric patients, including autistic children and adults with a diagnosis of borderline and schizotypal personality disorder. Results suggest that "schizoid" children, despite their high scores on a measure of schizotypy, do not have schizophrenia spectrum disorder or that schizotypy is a heterogeneous condition.
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PMID:"Schizoid" personality in childhood: auditory P300 and eye tracking responses at follow-up in adult life. 796 32

Traditional models of the genetic transmission of human diseases have often assumed that the phenotype is a simple dichotomous trait, which is unrealistic for many psychiatric conditions, and may result in loss of valuable information. We describe a new model for complex phenotypes, implemented in the program COMDS, which subclassifies normal and affected individuals into polychotomies correlated with the underlying genetic liability to the disorder. The model is applied to 18 Scottish pedigrees ascertained for schizophrenia, in which auditory P300 latency had been measured as a possible correlate of the genetic predisposition to schizophrenia. The results suggest that there may be a major locus for schizophrenia, but that there are also other familial determinants, possibly a second modifier locus. In addition, the results indicate that auditory P300 latency may be a useful measure of the genetic predisposition to schizophrenia among asymptomatic relatives, although the relationship between P300 latency and the degree of genetic predisposition in clinical cases was not significant, presumably because other factors are operating on P300 latency. Because of the possible selection biases in this sample, there is a need to replicate these findings in systematically ascertained pedigrees.
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PMID:Segregation analysis of complex phenotypes: an application to schizophrenia and auditory P300 latency. 804 1

To examine psychophysiological features of MAP psychosis and schizophrenia, P300 component of event-related potentials during an oddball paradigm were recorded in 25 MAP psychotics and 25 schizophrenics. P300 component was evaluated using baseline-to-peak measurement and principal component analysis. P300 amplitude in MAP psychotics was smaller at Fz and Cz region than in the controls. Unlike schizophrenics, P300 amplitude in MAP psychotics was not smaller at Pz region than in the controls. P300 latency in MAP psychotics and schizophrenics were delayed. These results indicated that MAP psychotics have some biological changes in their central nervous system after the remission of acute psychotic state.
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PMID:P300 component of event-related potentials in methamphetamine psychosis and schizophrenia. 807 82

According to information processing theory, attention deficits appear to be a nuclear disorder in schizophrenia which the study has been renewed with the development of neurophysiology technique. The originality of our research was to study in a same subject Event-Related-Potentials in three different conditions: passive and active auditory oddball paradigm for Mismatch Negativity (MMN) and P 300, and a simple reaction time task with warming stimulus for the Contingent Negative Variation (CNV). The study was carried out among 20 schizophrenic subjects (paranoid subtype with acute exacerbation, DSM-III-R) and 20 healthy volunteers. Patients differed from controls as the following: a lower amplitude of N1-P2 components of the auditive evoked potentials, a lower amplitude of MMN (absent in 20% of the psychotic subjects), a lower amplitude and a longer latency of P300, and a lower amplitude of CNV. These results suggest a fundamental dysfunction of information processing which involves the early stages of automatic and voluntary attentional cognitive processes in schizophrenia.
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PMID:[The value of cognitive psychophysiological studies in a comprehensive approach to schizophrenia (treatment of information and attention capacities in acute-stage schizophrenia)]. 809 94

Because P300 is typically measured from an average of single trials, variations among individual trials may account for P300 amplitude reduction so often seen in patients with schizophrenia. We tested three hypotheses regarding single-trial contribution to small average P300s in schizophrenics: normal P300s are elicited on some trials and no P300s on others, all trials have consistently small P300s, or P300 latency varies over trials. Nineteen schizophrenics and 35 controls were tested on a two-tone auditory oddball event-related potential (ERP) paradigm. ERPs recorded from the parietal electrode (Pz) were subjected to a P300-screening procedure in which a 2 Hz half-sine wave template was moved across the electroencephalogram (EEG) to find the point of best fit. If, for the point of best fit, the EEG:Template covariance was greater in the signal epoch (280-600 msec) than in the noise epoch (610-930 msec), and if the EEG:Template correlation was statistically significant, the trial passed the P300-screen and was deemed to have a P300. Three types of average ERPs were constructed: Traditional Average from all good (artifact-free, correct response) trials, P300-Screen Average from all good trials that also passed the P300-screen, and Latency Adjusted Average by aligning the P300-screen trials at the latency of maximum covariance. Traditional average ERPs were significantly smaller in schizophrenics than in controls. The results of the P300-screen confirmed all three hypotheses: schizophrenics had fewer trials passing the P300-screen, smaller P300s on each trial, and P300s that were more variable in latency across trials.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Schizophrenics have fewer and smaller P300s: a single-trial analysis. 816 15

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

Based on a review of the literature, the article deals with the major biological markers of schizophrenia. Recent developments in molecular biology have shown a possible association between schizophrenia and various HLA markers (A1, A2, A9, A10, A28, B27, BW16), and a linkage--in several families--between the disease and some polymorphisms of chromosome 5. On the other hand, chromosome X might also be involved. Neuropathological abnormalities have often been found in the brains of schizophrenics, such as cellular alterations in the basal ganglia and the limbic structures. Investigations by means of CT-scan and Magnetic Resonance Imaging have pointed out an enlargement of cerebral ventricles and/or an atrophy of frontal areas, especially amongst patients with prominent negative symptoms. The dopaminergic hypothesis of schizophrenia reposes on the major following facts: the therapeutic efficiency of neuroleptics (dopaminergic antagonists); a positive correlation between plasma homovanillic acid (metabolite of dopamine) concentration and the severity of schizophrenic illness; a higher density of dopaminergic D2-receptors (revealed by Positron Emission Tomography thanks to specific radioligands), particularly in the striatum; and an abnormal plasmatic growth-hormone response to apomorphine (dopaminergic agonist). Central noradrenergic dysfunctions might also occur in paranoid schizophrenia, as underlined by higher cerebrospinal fluid levels of norepinephrine, and a lack of decrease of plasma 3-methoxy-4-hydroxy-phenylglycol (MHPG, metabolite of norepinephrine) after clonidine (alpha-2-adrenergic agonist) dispensation. Nevertheless, in patients with predominating negative symptoms, this is a trouble in serotoninergic functions which has been suggested. In the field of immunology, some findings such as alteration in lymphocytes populations (T4/T8, CD5), anti-cerebral auto-antibodies, abnormal lymphocytes responses to mitogens, decreased production of interleukin-2, have lead to two main hypotheses: autoimmunity and immunologic incompetence. On the other hand, electrophysiological studies have shown a hypovariability of alpha-rythm on the EEG; a lower amplitude of the component P300 from visual evoked potentials; sleep disorders such as a shorter rapid eye movement sleep latency and a decreased total slow-wave sleep percent; irregular smooth pursuit eyes-movements; an electrodermal response according to either the hyper-responder either the non-responder type. At last, troubles in sensory integration, motor coordination and attention have also been demonstrated. All those many findings outline the heterogeneity of schizophrenic disorders.
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PMID:[Biological markers in schizophrenia]. 830 20

Schizophrenic subjects (N = 30) performed less well than controls (N = 30) on neuropsychological tests sensitive to frontal and temporal lobe impairment and showed prolonged latency of the P300 event-related potential. Relatives of schizophrenic probands were also tested. Relatives with an abnormal P300 had a similar range of neuropsychological deficits as were found in the schizophrenic group and relatives with a normal P300 response performed as well as the normal control group. The results suggest that neurophysiological and neuropsychological testing of relatives may help to clarify the mode of inheritance of schizophrenia in some families.
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PMID:Neuropsychological and P300 abnormalities in schizophrenics and their relatives. 833 46


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