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

A group of 16 chronic schizophrenic subjects were compared with 15 age-matched control subjects for interocular transfer of movement after-effects. Contrary to the hypothesis that schizophrenic subjects would show a deficit on this measure schizophrenics showed increased transfer compared to the controls. This effect is not due to response perseveration and is not correlated with length of hospitalization, age or dose of antipsychotic drugs. It is suggested that the effect reflects a deficit in 'inhibitory processes' in schizophrenia.
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PMID:Interocular transfer of movement after-effects in schizophrenia. 48 76

Magnetic resonance imaging was used to assess prefrontal brain structure in 17 schizophrenic, 18 psychiatric control, and 19 normal control subjects of comparable age, social background, and educational status, while three neuropsychological measures were used to assess prefrontal functioning. Schizophrenic patients had significantly smaller prefrontal areas than both psychiatric control and normal control subjects in all three planes. When posterior brain area and temporal lobe were entered into statistical analysis as covariates, they did not explain the prefrontal deficits. Schizophrenic patients made more perseveration errors on the Wisconsin Card Sorting Task and had fewer correct responses on the Spatial Delayed Response Task than normal control subjects. Schizophrenic patients performed more poorly than psychiatric control subjects on the Block Design Test. No group differences were found on three other nonfrontal tasks. These data lend some support to the role of prefrontal deficits in the development of schizophrenia.
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PMID:An evaluation of structural and functional prefrontal deficits in schizophrenia: MRI and neuropsychological measures. 136 15

The purpose of this study was to evaluate the role of attention in the cognitive abnormalities of schizophrenia. Controlling for attention by analysis of covariance (ANCOVA) had very little effect on the differences between 15 schizophrenic patients and 14 controls in regard to recently acquired, long-term episodic memory recall or remote semantic memory retrieval. Differences between the patients and controls on the percent perseverative response of the Wisconsin Card Sorting Test (WCST) were eliminated. These data suggest that deficits in attention may not underlie impaired recall of newly acquired information in schizophrenia or in the retrieval of information from remote, semantic memory, even under circumstances requiring more effortful processing. The data also suggest a contribution of attentional deficits to perseveration in schizophrenia.
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PMID:Attention and higher cortical functions in schizophrenia. 182 Dec 43

Schizophrenics and controls were compared on a computerized test of attentional set-shifting which provides a componential analysis of the Wisconsin Card Sort Test and has previously been shown to be sensitive to frontal lobe dysfunction and Parkinson's disease. The main test was of extra-dimensional shifting where subjects are required to shift response to an alternative perceptual dimension. In one condition, termed 'perseveration', subjects are required to shift to a novel dimension and ignore the previously relevant one. In the other condition, termed 'learned irrelevance', subjects are required to shift to the previously irrelevant dimension and ignore a novel one. Chronic medicated schizophrenics (N = 32) show a highly significant impairment on the perseveration but not the learned irrelevance condition, as compared to normal age and IQ matched controls (N = 24). This was true even of a subgroup of patients with preserved IQ. The impairments in attentional set-shifting failed to correlate with patients' scores on the Mini-Mental State Examination (mean; S.D. 26.8; 1.8) or with scores on a test of recognition memory. These results provide evidence for a specific deficit in a set-shifting test of executive function and support a hypothesis of frontostriatal dysfunction in schizophrenia.
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PMID:Neuropsychological evidence for frontostriatal dysfunction in schizophrenia. 748 Apr 41

Many forms of psychopathology in higher animals and humans include the production of maladaptive, repetitive behaviour. Behaviour which is both repetitive and excessive in amount can be described as stereotyped whereas behaviour which represents a restriction of behavioural possibilities without excessive production can be described as perseverative. Both types of repetition can result from pathology in the neural mechanisms which control either the production of motor output or the organisation of behaviour at a higher level. A number of forms of repetitive behaviour can be induced environmentally. Confinement in adulthood results in a functional disorder which rapidly dissipates when normal conditions are restored but confinement in infancy may have a permanent effect on the organism's ability to interact in a flexible and creative way with its environment. The permanence of these disorders suggests that the environment can affect the way in which the nervous system develops. Repetitive behaviour is also a feature of mental illness including schizophrenia, autism, OCD, addiction and some neurological disorders including frontal lobe lesions, Tourette's syndrome and PD. In experimental studies in animals, stereotyped behaviour seems to be related mainly to excess dopaminergic activity in the basal ganglia while perserverative behaviour can be produced by lesions of the frontal lobes. It is supposed that the level of dopamine activity in the basal ganglia affects the baseline level of behavioural activation such that excess activation results in the excessive execution of the most probable response to the environment to the exclusion of other possibilities (i.e. stereotypy) while deficient activation results in the production of only a few responses which can exceed the necessary activation level (i.e. perseveration). In either case behaviour is 'stimulus-bound', being driven by only the most salient feature of the environment. The symptoms of PD result from inadequate levels of dopamine in the basal ganglia while the stimulant psychoses result from excessive availability of dopamine. The frontal lobes have a modulating effect on (i) the activation of motor activity by the basal ganglia, (ii) in the generation of self-initiated behaviour, i.e. volition, and (iii) in the neural mechanisms which permit different modes of neural function (e.g. perceiving, remembering or thinking) to be identified. Failures in these three functions could result in excessive and repetitive motor activity, stimulus-bound behaviour, the paucity of volitional and creative behaviour, and the perceptual and experiential symptoms of psychosis.
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PMID:The psychology of perserverative and stereotyped behaviour. 783 78

Correlational approaches that examine the relation between neuropsychological measures and brain morphology or physiology in schizophrenia have yielded inconsistent results. This may be due in part to difficulties in ascertaining precisely to what degree each measure deviates from its genetically and environmentally determined potential level. We attempted to surmount this problem in a paradigm involving monozygotic twin pairs discordant for schizophrenia. In this paradigm, the difference score between the unaffected member and affected member of a twin pair should represent the degree of pathologic involvement irrespective of actual level. In correlating intrapair difference scores of anatomic structures measured from magnetic resonance imaging (n = 15) and prefrontal regional cerebral blood flow (rCBF) (n = 10) with cognitive abilities (after partialing IQ), we found strong associations between (1) the left hippocampus and a parameter of verbal memory, and (2) prefrontal rCBF with symptom scores and perseveration on the Wisconsin Card Sorting Test. These results support other research implicating medial temporal and prefrontal regions as important in the symptomatic expression and cognitive failures of schizophrenia. Overall, however, there was a relative paucity of significant associations between neuroanatomic and neurocognitive variables. This may have been due to the relatively restricted ranges of hippocampal size or cognitive ability found in this sample.
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PMID:Relations between neuropsychological performance and brain morphological and physiological measures in monozygotic twins discordant for schizophrenia. 804 29

The aim of this study was to examine whether specific forms of formal thought disorder distinguish schizophrenia from schizophreniform and schizoaffective psychoses. The sample was composed of 82 consecutively admitted patients with schizophrenic symptoms. Of these, 28 had a diagnosis of schizophrenia by RDC and DSM-IIIR criteria, 28 a diagnosis of schizophrenia by RDC but not DSM-IIIR (consequently they were labeled schizophreniform), and 26 a diagnosis of manic schizoaffective disorder by RDC criteria. They were assessed by a semi-structured interview for schizophrenia, by scales for positive and negative symptoms (SAPS and SANS) and by prognostic indicators. The assessment of thought disorder was carried out by using the Thought, Language and Communication scale (TLC). The schizophrenic patients showed higher global scores on formal thought disorder, and some of its subtypes were 'most specific' to schizophrenia (poverty of speech, poverty of content of speech, illogicality, tangentiality and perseveration). Schizophrenics had more loose associations than schizophreniforms. Manic schizoaffectives had higher scores on positive versus negative formal thought disorder than schizophreniforms. We suggested that the assessment of disordered thinking by the TLC may facilitate the differential diagnosis of psychotic disorders during the acute phase of the illness.
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PMID:Does formal thought disorder differ among patients with schizophrenic, schizophreniform and manic schizoaffective disorders? 839 47

The purpose of this study was to examine the factor structure of the Wisconsin Card Sorting Test (WCST). The scores of 22 patients with schizophrenia, 20 patients with chronic alcoholism, and 16 normal control subjects were entered into a principal components analysis, which yielded three factors: Perseveration, Inefficient Sorting, and Nonperseverative Errors. WCST performance of seven patients with lesions invading the dorsolateral prefrontal cortex, available from another study, provided criterion validity for the Perseveration factor and, less strongly, for the Inefficient Sorting factor. Two patterns of performance characterized the three patient groups: the schizophrenic group and frontal lobe group had the highest Perseveration factor scores, whereas the alcoholic group had the highest Inefficient Sorting scores; the Nonperseverative Errors factor showed no significant group differences. Construct validity of these factors involved assessing, in all but the frontal group, the degree of overlap (convergent validity) and separation (discriminant validity) of each WCST factor with scores from tests of other cognitive functions. The convergent and discriminant validity of the Perseveration factor, but not the remaining two factors, received support only within the group of schizophrenic patients.
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PMID:Factors of the Wisconsin Card Sorting Test as measures of frontal-lobe function in schizophrenia and in chronic alcoholism. 848 76

A principal component analysis of Wisconsin Card Sorting Test (WCST) scores has recently shown three factors. Only the Perseveration factor may measure the activity of the dorsolateral prefrontal cortex in schizophrenic patients. Liddle has hypothesized that a dysfunction in this area is specifically related to the negative syndrome and not to other schizophrenic syndromes (positive and disorganization). The factor analysis of the WCST was replicated with similar results in 38 schizophrenic or schizoaffective patients. In the total group, the correlation between the negative syndrome and the Perseveration factor did not reach significant levels. In the patients with a DSM-III-R diagnosis of schizophrenia (n = 30), the correlations did reach significant levels.
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PMID:Schizophrenic syndrome and Wisconsin Card Sorting Test dimensions. 853 11

Perseveration in schizophrenia may take a variety of forms, which can be conceptualized as varying manifestations of an underlying neurocognitive deficit. Comparative studies have demonstrated higher than normal levels of perseverative responding among schizophrenia patients on capacity-demanding tasks, including prompted discourse, reversal learning, and the generation of guessing sequences. There is little evidence that perseveration is associated with deficit signs of schizophrenia. However, perseveration appears to covary with both positive thought disorder and voluntary motor disturbance. Perseveration in schizophrenia thus appears to be a productive sign elicited by a failure to mobilize cognitive resources in situations requiring controlled information processing and the concomitant inhibition of activated but task-inappropriate responses. An information-processing model proposed by Shallice (1988) attributes perseveration to a failure of a higher level executive control system to modulate a lower level response selection system under a requirement for novel response generation. This model suggests that perseveration is the consequence of a failure of frontal specification of striatal outputs during controlled processing, resulting in the continued reselection of previously activated outputs.
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PMID:Perseveration in schizophrenia. 905 Jan 13


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