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

Cognitive deficits associated with frontal lobe dysfunction are a determinant of long-term disability in schizophrenia and are not effectively treated with available medications. Clinical studies show that many aspects of these deficits are transiently induced in healthy individuals treated with N-methyl-D-aspartate (NMDA) antagonists. These findings and recent genetic linkage studies strongly implicate NMDA receptor deficiency in schizophrenia and suggest that reversing this deficiency is pertinent to treating the cognitive symptoms of schizophrenia. Despite the wealth of behavioral data on the effects of NMDA antagonist treatment in humans and laboratory animals, there is a fundamental lack of understanding about the mechanisms by which a general state of NMDA deficiency influences the function of cortical neurons. Using ensemble recording in freely moving rats, we found that NMDA antagonist treatment, at doses that impaired working memory, potentiated the firing rate of most prefrontal cortex neurons. This potentiation, which correlated with expression of behavioral stereotypy, resulted from an increased number of irregularly discharged single spikes. Concurrent with the increase in spike activity, there was a significant reduction in organized bursting activity. These results identify two distinct mechanisms by which NMDA receptor deficiency may disrupt frontal lobe function: an increase in disorganized spike activity, which may enhance cortical noise and transmission of disinformation; and a decrease in burst activity, which reduces transmission efficacy of cortical neurons. These findings provide a physiological basis for the NMDA receptor deficiency model of schizophrenia and may clarify the nature of cortical dysfunction in this disease.
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PMID:NMDA receptor hypofunction produces concomitant firing rate potentiation and burst activity reduction in the prefrontal cortex. 1515 46

The inability to modulate processing time in conjunction with varying difficulty levels may be a core component of schizophrenia's cognitive deficit. In this study we used a parametric design to demonstrate this group's inability to increase and decrease response times in association with varying levels of task demand during auditory and visual recognition tasks. Unlike participants with schizophrenia, healthy volunteers responded to increasing levels of difficulty and high error by robustly increasing their average response times. In the group with schizophrenia, the greater the correlation between a subject's Response-Time and error rate the better was the subject in his/her overall discrimination accuracy. The higher their correlations the better they performed across all levels of difficulty in both modalities. The schizophrenia group's tendency to process high and low error conditions with similar behavioral resources may reflect a relatively static, non-dynamic cognitive repertoire.
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PMID:Parametric study of accuracy and response time in schizophrenic persons making visual or auditory discriminations. 1529 20

Many neuropsychological studies have described deficits of memory and executive functions in patients with schizophrenia, and the severity of these deficits seems to be determinant in predicting the community outcome of these patients [Schizophr. Bull. 26 (2000) 119]. However, neuropsychological evaluation does not provide valuable information about how the cognitive deficits directly affect daily living, that is, which cognitive deficit affects which behavior. The present study aimed at determining whether executive dysfunction in schizophrenia could be directly measured by analyzing three activities of daily living (ADL), in addition to assessing the ecological validity of commonly used neuropsychological tests. Within specific ADL (choosing a menu, shopping the ingredients, cooking a meal), the sequences of behaviors that have been performed by 27 control subjects and 27 patients with schizophrenia were both analyzed by using a preset optimal sequence of behavior. When compared with control subjects, patients with schizophrenia showed more omissions when choosing the menu, more sequencing and repetitions errors during the shopping task, and more planning, sequencing, repetition and omission errors during the cooking task. These behavioral errors correlated significantly with negative, but not with positive symptoms of the patients. Furthermore, they also correlated with the poor performances on executive neuropsychological tests, especially those sensitive to shifting and sequencing abilities, but not with memory tests. These results suggest that executive deficits in schizophrenia may specifically affect ADL and that such deficits can be quantitatively assessed with a behavioral scale of action sequences.
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PMID:Assessment of executive dysfunction during activities of daily living in schizophrenia. 1546

Eighty-five patients (52 male, 33 female, mean age 28.9 years) with slowly progressive schizophrenia with predominantly positive (pseudopsychopathic type, ICD-10 item F21.4)--79 patients and/or predominantly negative ("poor symptoms" schizophrenia, F20.6)--6 patients symptoms, were studied. All patients referred to the psychiatric clinic with refusal reactions. Depending on the psychological and behavioral mechanisms developing on the base of negative changes the refusal reactions have been divided into capitulation, avoidance and absenteeism subtypes. Their clinical heterogeneity was determined by the ratio of structure of schizophrenia-related personality disorders and cognitive deficit. Negative disorders in capitulation refusal reaction manifest in patients as "psychosthenic-like" personality with accentuation of dependent personality features and operational cognitive deficit. Avoidance subtype was observed in patients with schizoid (autistic or eccentric) personality changes and predominantly dynamic cognitive deficit. Absenteeism subtype was found in weak-will individuals and mainly motivational cognitive deficit.
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PMID:[The background for development of refusal reactions in schizophrenics]. 1549 Sep 35

One of the primary goals in the NIMH initiative to encourage development of new interventions for cognitive deficits in schizophrenia, Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS), has been to develop a reliable and valid consensus cognitive battery for use in clinical trials. Absence of such a battery has hampered standardized evaluation of new treatments and, in the case of pharmacological agents, has been an obstacle to FDA approval of medications targeting cognitive deficits in schizophrenia. A fundamental step in developing such a battery was to identify the major separable cognitive impairments in schizophrenia. As part of this effort, we evaluated the empirical evidence for cognitive performance dimensions in schizophrenia, emphasizing factor analytic studies. We concluded that seven separable cognitive factors were replicable across studies and represent fundamental dimensions of cognitive deficit in schizophrenia: Speed of Processing, Attention/Vigilance, Working Memory, Verbal Learning and Memory, Visual Learning and Memory, Reasoning and Problem Solving, and Verbal Comprehension. An eighth domain, Social Cognition, was added due to recent increased interest in this area and other evidence of its relevance for clinical trials aiming to evaluate the impact of potential cognitive enhancers on cognitive performance and functional outcome. Verbal Comprehension was not considered appropriate for a cognitive battery intended to be sensitive to cognitive change, due to its resistance to change. The remaining seven domains were recommended for inclusion in the MATRICS-NIMH consensus cognitive battery and will serve as the basic structure for that battery. These separable cognitive dimensions also have broader relevance to future research aimed at understanding the nature and structure of core cognitive deficits in schizophrenia.
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PMID:Identification of separable cognitive factors in schizophrenia. 1553 5

Cognitive dysfunction is an important feature of schizophrenia and bipolar disorder. There is uncertainty about the relative magnitude of cognitive deficits in these disorders. We evaluated a total of 446 individuals: 229 with schizophrenia, 117 with bipolar disorder, and 100 controls without a history of psychiatric disorder. All participants were administered the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), a cognitive screening battery that evaluated immediate verbal memory, visuospatial/constructional abilities, attention, language, and delayed memory. A comparison of the three groups showed significant differences on the RBANS total score and all of the measured domains. In all of the comparisons, the schizophrenia group obtained the lowest scores, followed by the bipolar disorder group, and then the individuals without psychiatric disorder. In an analysis of covariance of RBANS total scores with the patient samples, the difference between schizophrenia and bipolar disorder remained significant after controlling for a range of demographic and clinical variables. Both schizophrenia and bipolar disorder are associated with significant cognitive impairments, but those in schizophrenia are more severe. Cognitive deficits may be an appropriate target of treatment interventions in these disorders.
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PMID:Cognitive functioning in schizophrenia and bipolar disorder: comparison of performance on the Repeatable Battery for the Assessment of Neuropsychological Status. 1557 84

A lot of progress has been made in the treatment of schizophrenia against hallucinations and delusions. However, Schizophrenia still remains a highly disabling disease causing tremendous deficits in social- and vocational functioning. Cognitive deficits are known since the early 90's as a further core feature of schizophrenia, and it has been shown that social- and vocational dysfunctions are closely related to neurocognitive deficits. Whether those findings bear a potential for therapeutic implications still needs to be shown. In this overview therapeutic interventions with respect to cognitive deficits and their effectiveness and their role for vocational rehabilitation will be summarized.
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PMID:[Neurocognition, psychosocial outcome and vocational integration]. 1558 14

Although amphetamine treatment has been shown to promote recovery of motor function in animals with cortical ablations, the potential therapeutic effect of amphetamine on processes other than motor control, such as attention and working memory, has been relatively unexplored. Accordingly, we investigated the beneficial effect of D-amphetamine treatment in animals with dorsal prefrontal cortex lesions (dPFC) compared with sham controls on a novel combined attention-memory task (CAM) that simultaneously measures attention to a visual stimulus and memory for that stimulus. The dPFC group was impaired in their ability to correctly detect the visual stimulus. Although this deficit occurred together with increased omissions and slow response latencies, these associated deficits largely recovered within the 10 post-operative baseline sessions revealing a selective attentional deficit in this group of animals. Nonetheless, the dPFC lesion did not substantially affect the working memory component of the task. The systemic administration of d-amphetamine served to ameliorate the attentional deficit in the dPFC group at the low dose only (0.2 mg/kg). By contrast, the dPFC group were less sensitive to the detrimental effects of the high dose (0.8 mg/kg) on any aspect of task performance. However, despite improving attention to the visual stimulus, D-amphetamine did not improve memory for that stimulus which instead appeared to deteriorate. The results provide apparently the first demonstration that low doses of D-amphetamine can ameliorate an attentional deficit in animals with selective dPFC lesions and may be a useful model of cognitive deficit in ADHD, schizophrenia or frontal brain injury.
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PMID:D-Amphetamine remediates attentional performance in rats with dorsal prefrontal lesions. 1568 Jan 98

Previous research has reported cognitive impairment in patients with schizophrenia and antisocial personality disorder (APD), the two psychiatric illnesses most implicated in violent behaviour. Previous studies have focused on either group exclusively, and have been criticized for procedural inadequacies and sample heterogeneity. The authors investigated and compared neuropsychological profiles of individuals with APD and violent and nonviolent individuals with schizophrenia in a single investigation. The study involved four groups of subjects: (i) individuals with a history of serious violence and a diagnosis of APD, (ii) individuals with a history of violence and schizophrenia, (iii) individuals with schizophrenia without a history of violent behaviour and (iv) healthy control subjects. All study groups were compared on a neuropsychological battery designed to assess general intellectual function, executive function, attention, and processing speed. Cognitive deficits were more widespread among individuals with schizophrenia regardless of history of violence, compared with those with APD. Significant impairment in patients with APD was limited to processing speed. Violent individuals with schizophrenia demonstrated poorer performance than their nonviolent schizophrenia peers on a measure of executive function. Different cognitive impairments are manifested by individuals with APD and schizophrenia with violent behaviours, suggesting differences in underlying pathology. Furthermore, cognitive impairment appears to be more a feature of schizophrenia than of violent behaviour, although there is evidence that a combination of schizophrenia and violent behaviour is associated with greater cognitive deficits.
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PMID:A neuropsychological investigation into violence and mental illness. 1569 49

Recognition and treatment of schizophrenia has largely focused on positive symptoms of the disorder, such as delusions, hallucinations, and disorganization. However, other important symptoms, such as depression, cognition, and social functioning, have not received comparable attention. Fifty percent of schizophrenic patients suffer from comorbid depression, which is a major risk factor for suicide in this population, while 10% to 25% suffer from comorbid obsessive-compulsive disorder. Cognitive deficits commonly observed in patients with schizophrenia include problems with concentration, attention, and memory, as well as problem-solving and verbal skills. These deficits are observed at early stages of the illness and can predict deficits in functional capabilities, such as occupational and social skills, educational attainment, and the ability to live independently. The severity of such impairments affects all patient in this population, including up to 10% of patients working full time and up to one third of those working part time. In light of the debilitating effects of depression, cognitive impairment, and other aspects of affective functioning on the quality of life of patients with schizophrenia, physicians need to partner with their patients to address these concerns and determine an appropriate treatment regimen. This can be done with simple functional-based cognitive questioning, the use of evidence-based psychosocial practices, and psychoeducation on the many pharmacotherapeutic options. It is recommended that depressive or suicidal symptoms of schizophrenia be treated with an antidepressant or mood stabilizer only if the symptoms have not subsided after treatment of the psychosis with an atypical antipsychotic. Additionally, relative to older medications, atypicals have demonstrated benefit in improving some of the cognitive impairments.
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PMID:Optimizing treatment of schizophrenia. Enhancing affective/cognitive and depressive functioning. 1580 22


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