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

This study explored the factor structure of the Wisconsin Card Sorting Test (WCST). Scores from 197 participants with schizophrenia or schizoaffective disorder were subjected to an exploratory factor analysis that yielded three factors: Perseveration, Nonperseverative Error, and Inefficient Sorting. Comparison with two previous factor analyses revealed remarkable factorial invariance. Correlations with subject and illness characteristics, symptom dimensions, and work performance demonstrated predictive and divergent validity for the three factors. However, a representative item from each factor yielded similar correlations with very little loss of power suggesting that the factors are composed of highly redundant items. When data reduction is necessary, schizophrenia researchers are justified in using three variables: perseverative error, nonperseverative error, and failure to maintain set, to represent WCST performance.
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PMID:Wisconsin Card Sorting Test dimensions in schizophrenia: factorial, predictive, and divergent validity. 952 88

The aim of this study was to explore the factorial structure of the Wisconsin Card Sorting Test (WCST) and to identify the dimensions of deficit in schizophrenia. WCST scores in patients with schizophrenia and schizophrenia-related psychosis (n = 292), 1st degree relatives of schizophrenic patients (n = 91), and normal controls (n = 141) were subjected to a principal factor analysis followed by orthogonal rotation. This led to 3 factors, perseveration, failure to maintain set, and idiosyncratic sorting. The detected factor structure was found to be invariant across the schizophrenic and control subsamples. Moreover, it replicated previous findings from 2 smaller samples. Only perseverations and, to a lesser degree, idiosyncratic sorting appeared to differentiate schizophrenic patients from comparisons. Only perseveration had good sensitivity and specificity, as well as the most robust significant correlations with estimates of IQ, attention, and other measures of executive functioning. Thus, perseveration appears to be the most diagnostically useful and characteristic WCST feature of schizophrenia.
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PMID:Factor structure of the Wisconsin Card Sorting Test: dimensions of deficit in schizophrenia. 955 75

It remains unclear how impaired insight and neurocognitive impairment are related to one another in schizophrenia. In order to examine this relationship, subjects with schizophrenia or schizoaffective disorder were classified as having 'impaired' (n=38) or 'unimpaired' (n=43) insight based on their insight rating on the Positive and Negative Syndrome Scale (PANSS). Their performance on neuropsychological tests of global function, executive function, memory and vigilance was then compared. Multivariate analyses followed by Scheffe tests indicated that subjects with impaired insight performed less well on the Wisconsin Card Sorting Test, demonstrating poorer abstract flexibility and heightened perseveration. No differences were found between the groups with regard to global cognitive function, memory or vigilance. This suggests that insight is closely linked to deficits in executive function, and that it may be associated with the compromise of frontal lobe function.
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PMID:Neurocognitive function and insight in schizophrenia: support for an association with impairments in executive function but not with impairments in global function. 957 Apr 91

Perseverations have been associated with frontal lobe impairment and are often observed among schizophrenia patients. We assessed perseverations in schizophrenia patients (N = 71) using the Wisconsin Card Sorting Test (WCST) and a new Rorschach perseveration scale which yields three perseveration scores. We also compared the results of the schizophrenia patients with those of a normal comparison group (N = 71). We found that schizophrenia patients demonstrated a high number of perseverations on both the WCST and the Rorschach perseveration scale when compared to the normal comparison subjects. Among schizophrenia patients, WCST perseverative responses were significantly correlated with Rorschach-derived stuck-in-set perseverations, WAIS-R Vocabulary scores and negative symptom ratings. No significant differences in any of the measures of perseveration were found to be associated with diagnostic subtype. Finally, WCST and Rorschach measures for the schizophrenia and normal comparison participants were entered into a logistic regression. The WCST total errors and the three Rorschach perseveration measures resulted in the correct classification of 89.4% of the total cases, with a sensitivity of 91%, specificity of 91% and positive predictive power of 87.8%. These data provide evidence that perseverative behavior is widely observed in schizophrenia patients using a variety of instruments. The authors discuss the benefit of using multiple measures of perseveration in schizophrenia research.
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PMID:A multimethod approach to assessing perseverations in schizophrenia patients. 978 46

This review covers some recent findings of the electrophysiological mechanisms through which mesocortical dopamine modulates prefrontal cortical neurons. Dopamine has been shown to modulate several ionic conductances located along the soma-dendritic axis of prefrontal cortical pyramidal neurons. These ionic currents include high-voltage-activated calcium currents and slowly inactivating Na+ and K+ currents. They contribute actively in processing functionally segregated inputs during synaptic integration. In addition, dopamine mainly depolarizes the fast-spiking subtype of local GABAergic interneurons that connect the pyramidal neurons. This latter action can indirectly control pyramidal cell excitability. These electrophysiological data indicate that the actions of dopamine are neither "excitatory" nor "inhibitory" in pyramidal prefrontal cortex neurons. Rather, the actions of dopamine are dependent on somadendritic loci, timing of the arrival of synaptic inputs, strength of synaptic inputs, as well as the membrane potential range at which the PFC neuron is operating at a given moment. Based on available electrophysiological findings, a neuronal model of the pathophysiology of schizophrenia is presented. This model proposes that episodic hypo- and hyperactivity of the PFC and the associated dysfunctional mesocortical dopamine system (and their interconnected brain regions) may coexist in the same schizophrenic patient in the course of the illness. We hypothesize that the dysfunctional mesocortical dopamine input to the PFC may lead to abnormal modulation of ionic channels distributed in the dendritic-somatic compartments of PFC pyramidal neurons that project to the ventral tegmental area and/or nucleus accumbens. In some schizophrenics, a reduction of mesocortical dopamine to below optimal levels and/or a loss of local GABAergic inputs may result in a dysfunctional integration of extrinsic associative inputs by Ca2+ channel activity in the distal dendrites of PFC pyramidal neurons. This may account for the patients' distractibility caused by their inability to focus only on relevant external inputs. In contrast, in acute stress or psychotic episodes, an associated abnormal elevation of mesocortical dopamine transmission may greatly influence distal dendritic Ca2+ channel-mediated signal-processing mechanisms. This can enhance possible reverberative activity between adjacent interconnected pyramidal neurons via the effects of dopamine on the slowly inactivating Na+, K+, and soma-dendritic Ca2+ currents. The effects of high levels of PFC dopamine in this case may contribute to behavioral perseveration and stereotypy so that the patients are unable to use new external cues to modify ongoing behaviors.
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PMID:Developing a neuronal model for the pathophysiology of schizophrenia based on the nature of electrophysiological actions of dopamine in the prefrontal cortex. 1043 66

We evaluated psychiatric symptoms and neurocognitive functioning among 25 institutionalized and 25 outpatient DSM-IV-diagnosed schizophrenia patients, as well as 25 middle-aged and elderly normal comparison subjects. All subjects were assessed with the Positive and Negative Syndrome Scale, Hamilton Rating Scale for Depression, modified Simpson-Angus Extrapyramidal Symptom Scale, the Abnormal Involuntary Movement Scale, and the Mattis Dementia Rating Scale (DRS). The two patient groups had similar levels of depressive symptoms, but the institutionalized patients had more severe positive and negative symptoms and were on higher doses of neuroleptic medication. The institutionalized patients had significantly more cognitive impairment on the DRS than outpatients and normal comparison subjects, particularly on the subscales of initiation/perseveration, conceptualization, and memory. Results are discussed in terms of the possible neuropathology associated with cognitive impairment in chronic schizophrenia.
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PMID:Cognitive deficits and psychopathology in institutionalized versus community-dwelling elderly schizophrenia patients. 1044 49

Several neuropsychological models of schizophrenia have regarded the syndrome as a disorder of the left hemisphere. However, discrepant experimental findings have been reported. It has been proposed that the different psychopathological dimensions of the syndrome are associated with distinct patterns of hemispheric imbalance. The present study was aimed at exploring relationships of psychopathological dimensions of schizophrenia with fronto- and temporo-hippocampal functioning of either hemisphere in 42 drug-free patients with a DSM-III-R diagnosis of schizophrenia. For the negative dimension, an inverse correlation with the performance on a verbal conditional associative task was found, consistent with the presence of a left fronto-hippocampal impairment in this dimension. As to the positive dimension, our results showed a direct correlation with perseveration on a verbal self-ordered pointing task, suggesting a hyperactivation of the left-hemisphere in this dimension. The disorganisation was found to be associated with a faster execution of a spatial memory task, probably reflecting increased perceptual priming and a right temporo-hippocampal disinhibition.
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PMID:Hemispheric asymmetry and psychopathological dimensions in drug-free patients with schizophrenia. 1061 53

The objective of this study was to compare differences in behavioral, psychiatric, and cognitive status among geropsychiatric inpatients with Alzheimer's, vascular, alcohol-induced, and mixed dementia. Participants included 150 patients with dementia consecutively admitted to an acute geropsychiatric inpatient unit. Measures included the Mini-Mental State Examination, Cohen-Mansfield Agitation Inventory, Cumulative Illness Rating Scale, Basic and Independent Activities of Daily Living, Positive and Negative Syndrome Scale for Schizophrenia, and the Initiation/Perseveration subscale of the Dementia Rating Scale. No significant differences existed in the character or severity of agitation among patients with Alzheimer's, vascular, alcohol-related and mixed dementia. Interestingly, patients with vascular dementia compared to patients with other dementias admitted for behavioral disturbances were less cognitively impaired and more medically burdened.
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PMID:Behavioral disturbances in geropsychiatric inpatients across dementia types. 1075 8

Previous research indicates that verbal learning and memory deficits are among the most severe cognitive deficits observed in schizophrenia. However, the concomitant patterns of regional brain function associated with these deficits in schizophrenia are not well understood. The present study examined verbal-memory performance and simultaneous relative glucose metabolic rates (rGMR) with FDG PET in 20 unmedicated schizophrenia patients who met stringent memory-performance criteria and 32 age- and sex-matched normal volunteers. On a modified version of the California Verbal Learning Test, patients recalled fewer correct words using a semantic-clustering strategy and exhibited more intrusions compared with normal subjects. However, patients had higher serial-ordering strategy scores, indicating their use of a less efficient organizational strategy. Among patients, greater use of the serial-ordering strategy was associated with decreased rGMR in frontal cortex and increased rGMR in temporal cortex. Patients had lower rGMR primarily in frontal and temporal cortex, but not parietal and occipital lobe regions. Patients also exhibited hypofrontality (lower ratio of frontal to occipital rGMR) compared with normal subjects. Among the patients, more severe hypofrontality was associated with increased perseveration errors.
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PMID:Hypofrontality in unmedicated schizophrenia patients studied with PET during performance of a serial verbal learning task. 1082 13

Performance on the Wisconsin Card Sort Test (WCST) of patients with schizophrenia, Parkinson's disease (PD), and Huntington's disease (HD) was simulated by a neural network model constructed on principles derived from neuroanatomic loops from the frontal cortex through the basal ganglia and thalamus. The model provided a computational rationale for the empirical pattern of perseverative errors associated with frontal cortex dysfunction and random errors associated with striatal dysfunction. The model displayed perseverative errors in performance when the gain parameter of the activation function in units representing frontal cortex neurons was reduced as an analog of reduced dopamine release. Random errors occurred when the gain parameter of the activation function in units representing striatal neurons was reduced, or when the activation level was itself reduced as an analog of a striatal lesion. The model demonstrated that the perseveration of schizophrenic, Huntington's, and demented Parkinsonian patients may be principally due to ineffective inhibition of previously learned contextual rules in the frontal cortex, while the random errors of Parkinson's and Huntington's patients are more likely to be due to unsystematic errors of matching in the striatum. The model also made specific, empirically falsifiable predictions that can be used to explore the utility of these putative mechanisms of information processing in the frontal cortex and basal ganglia.
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PMID:A computational model of information processing in the frontal cortex and basal ganglia. 1093 75


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