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

It has been suggested that lack of awareness of illness in schizophrenia may result from deficits in executive function and/or an avoidant style of coping. To examine this question, 132 persons with schizophrenia spectrum disorders were rated as either "aware," "partially unaware" or "unaware" of: (a) their illness, (b) need for treatment and (c) consequences of disorder on the abbreviated Scale to Assess Unawareness of Mental Disorder. We next compared the performance of the aware, partially unaware and unaware groups on the "escape-avoidance" and "positive reappraisal" subtests of the Ways of Coping Questionnaire and on two tests of executive function: the Letter Number Sequencing Subtest of the WAIS III and Wisconsin Card Sorting Test. MANCOVA followed by ANCOVA and planned comparisons, controlling for age indicated that the participants who were unaware of symptoms, treatment need and consequences generally performed more poorly than the aware groups on tests of executive function. Participants unaware of symptoms also had a greater preference for positive reappraisal than aware or partially unaware participants. The participants unaware of the consequences of disorder endorsed a greater preference for escape-avoidance than the partially unaware participants. Implications for understanding the etiology of lack of awareness in schizophrenia are discussed.
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PMID:Insight in schizophrenia: associations with executive function and coping style. 1241 41

The aim of this study was to investigate the underlying structure of eight working memory tests used to assess prefrontal dysfunction in schizophrenia research [Letter-Number Span (LNS), Digit-Symbol Test (DST), Trail-Making Test B (TMT-B), Delayed Response Task (DRT) for spatial working memory, Subject Ordered Pointing Task (SOPT), Dual Tasking (DUAL), Continuous Performance Test (CPT)-Identical Pairs, Wisconsin Card Sorting Test (WCST)]. Sixty-six patients with schizophrenia showed significant working memory performance deficits in all tests when compared with 45 healthy controls. Performance was not systematically related to psychopathology. When differences in IQ were controlled, working memory deficits remained stable except in the WCST. Principal components analyses yielded three components for healthy controls: a comparator function of the central executive defined by a comparison of working memory content with information from the environment, an allocation of attentional resources function, and a maximum storage capacity function. The comparator and maximum storage functions could be replicated in the schizophrenia sample. However, the allocation function did not emerge as an independent component and was replaced by a component defined by the WCST. These findings suggest that working memory is not a unitary concept but rather should be conceptually differentiated as functions of transient storage/active rehearsal capacity and central executive manipulation supporting a previous suggestion proposed by Perry et al. [Schizophr. Bull. 27 (2001) 157].
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PMID:Dimensions of working memory dysfunction in schizophrenia. 1283 23

Letter fluency performance is less impaired than the category fluency performance in alphabetical-language speakers with schizophrenia. The purpose of this study was to determine whether the same pattern in the performance on the two verbal fluency tasks exists in subjects using a non-alphabetical language. In the Japanese orthography, there is one-to-one correspondence between sound (syllable) and graphemes ("kana" script), in contrast to one-to-many associations in alphabetical languages (e.g. English, French). The category fluency task (ANIMAL, FRUIT) and the letter fluency task ("KA", "TA" in "kana" script) were administered on 38 patients with schizophrenia and the equal number of normal controls. In order to examine the influence of psychotic symptoms on the verbal fluency performance, the Scale for the Assessment of Positive Symptoms (SAPS) and the Scale for the Assessment of Negative Symptoms (SANS) were administered. The patients performed significantly worse both in the letter- and category fluency tasks compared with control subjects. However, performance on the letter fluency task and category fluency task was similarly impaired in Japanese patients with schizophrenia, unlike the results in previous studies with alphabetical-language speakers. On the other hand, Alogia symptoms, as assessed by SANS, was a significant predictive variable in the regression model for the category fluency task score (ANIMAL), whereas the factor of the other domains of negative symptoms as a whole was a significant predictive variable in the model for the letter fluency task score (TA), which confirmed the findings in previous studies with alphabetical-language subjects. These results suggest that the pattern of impairment in the verbal fluency performance in schizophrenia is dependent on the specific language systems used by the patients although the degradation of the verbal fluency performance is influenced by some types of negative symptoms irrespective of the language system.
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PMID:Effect of orthography on the verbal fluency performance in schizophrenia: examination using Japanese patients. 1514 66

Performance on the Letter-Number Sequencing (LNS) and Wisconsin Card Sorting Tests (WCST) have been shown to be significantly correlated in patients with schizophrenia, a relationship postulated to be due to working memory demands of the two tests (Gold, Carpenter, Randolph, Goldberg, & Weinberger, 1997). An alternative explanation for the association between these two tests is their sorting demands, in that both require sorting of information albeit in slightly different ways. If the latter explanation is valid, then working memory tasks that do not require sorting or other conceptualization demands should be less predictive of WCST performance than LNS. These hypotheses were examined in 34 poor outcome patients with schizophrenia, one-half of whom were over the age of 65. Patients were evaluated on Digit Span Forward, spatial working memory, LNS, and the WCST. It was found that WCST performance was significantly associated with performance on the LNS but no other working memory task. Age related performance differences were greatest on the WCST Categories and floor effects were noted on this test in one-half of the subjects. Analyses predicting WCST Categories in subjects whose scores were greater than zero (n = 16) also demonstrated that LNS, but not Digit Span or spatial working memory (any delay) predicted WCST performance. These findings indicate that LNS may be an index of executive functioning, particularly in patients who cannot perform the WCST.
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PMID:Working memory performance in poor outcome schizophrenia: relationship to age and executive functioning. 1520 35

Letter- or semantically-cued verbal fluency tests (VFT) induce different, but overlapping activities in the prefrontal cortex (PFC) in healthy subjects. Functional differences between letter and semantic VFT may be important in elucidating the nature of language-related problems in schizophrenia since more profound impairment in semantically-cued retrieval may be suggestive of semantic system dysfunction specific to this disorder. However, the functional differences between the letter vs. semantic VFT on prefrontal metabolism in the subjects with schizophrenia have not been described. In the present study, we used near-infrared spectroscopy (NIRS) to assess hemoglobin concentration changes in the bilateral PFCs in subjects and controls. Sixteen subjects with schizophrenia and 19 healthy controls performed letter and semantic VFTs. Prefrontal hemodynamic changes were simultaneously monitored by NIRS. While healthy subjects performed both tasks equivalently, the subjects with schizophrenia showed more compromised performance in the semantic VFTs compared to the letter VFTs. NIRS measurement revealed that the pattern of PFC activation was greater during the letter VFT when compared to the semantic VFT in the healthy subjects, suggesting more prominent PFC involvement in letter-cued retrieval. In contrast, the subjects with schizophrenia showed the opposite pattern of activation, implying that the semantic mode of lexical access might impose greater cognitive demands on the PFC. The present study is the first to detect abnormal patterns of PFC activation in adults with schizophrenia in response to the distinct cognitive demands associated with letter and semantic VFT.
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PMID:Prefrontal activation during verbal fluency tests in schizophrenia--a near-infrared spectroscopy (NIRS) study. 1600 86

Organization of semantic memory, one of the domains of cognitive function, is impaired in patients with schizophrenia, and is predictive of functional outcomes. The Category Fluency Task (CFT) has been used to evaluate organization of long-term semantic memory by means of visualizing semantic associations in the form of 'cognitive map' and cluster structures. While atypical antipsychotic drugs (AAPDs) have been shown to ameliorate overall cognitive deficits, little is known about the efficacy of AAPDs for improving higher cognitive functions, such as semantic memory organization. The purpose of the present study was to determine if treatment with olanzapine or ziprasidone has beneficial influence on organization of semantic memory, as revealed by analysis of data from the CFT, in patients with schizophrenia. A retrospective analysis of an open-label trial was conducted for 33 patients with schizophrenia who were treated with either olanzapine or ziprasidone. Nineteen subjects were unmedicated at baseline. The CFT and Letter Fluency Task, as well as the Brief Psychiatric Rating Scale (BPRS) and Quality of Life Scale (QLS), were administered at baseline and 6 wk of the treatment. Semantic structures were obtained by multidimensional scaling analysis and hierarchical cluster analysis of verbal outputs from the CFT. At baseline, no meaningful dimension or cluster was observed in the semantic structure; however, knowledge-based dimensions (wild vs. domestic) appeared after treatment with olanzapine or ziprasidone. Cluster structures also became organized, especially after treatment with olanzapine. Scores of QLS, but not those of BPRS, improved during treatment with the AAPDs. These results suggest a facilitative influence of AAPDs on higher cognitive functions, such as organization of semantic memory, in patients with schizophrenia.
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PMID:Atypical antipsychotic drugs and organization of long-term semantic memory: multidimensional scaling and cluster analyses of category fluency performance in schizophrenia. 1631 5

The current study investigated the relationship between clinical evaluations of social functioning and neurocognitive test results, including various fluency tests for assessing divergent thinking, in patients with schizophrenia. The Optional Thinking Test (OTT) was used to measure the ability of individuals to conceive of alternatives. This test assesses alternative thinking, or the capacity to generate solutions to problems. The current study examined 36 schizophrenia patients and 25 normal subjects using the Mini-Mental State Examination (MMSE), the Rey Auditory Verbal Learning Test (RAVLT), the Letter Cancellation Test (LCT), the Letter and Category Fluency Tests, and the OTT for neurocognitive assessment, as well as the Positive and Negative Syndrome Scale (PANSS), the Global Assessment of Functioning (GAF), the Social Functioning Scale (SFS), and the Life Assessment Scale for the Mentally Ill - Interpersonal Relations (LASMI-I) for clinical measures. The schizophrenia patients had significantly poorer performances on the MMSE, RAVLT, LCT (time), fluency tests, and OTT than the controls. In the OTT, the proportions of classified strategies were indistinguishable between the schizophrenia patients and the controls. Alternative thinking, as measured by the OTT, was correlated with verbal fluency and attention but was not correlated with the social functioning scores (GAF, SFS, LASMI-I), whereas the Means-Ends Problem-Solving was correlated with the GAF in schizophrenia. Patients with schizophrenia could conceive of the same categories of alternatives as healthy people, but could not conceive as many alternatives.
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PMID:Relation between social functioning and neurocognitive test results using the Optional Thinking Test in schizophrenia. 1647 60

Transient working memory requires attention and temporary storage of information, whereas executive function working memory requires additional mental manipulation of that information. Working memory impairment is common in schizophrenia patients, but only some studies have found differential impairment in executive function working memory compared to transient working memory. We measured both types of working memory using the Digit Span forward (DF) and backward (DB) tasks in a large sample of schizophrenia patients (n=267) and normal comparison subjects (n=82); in the patients, we also examined associations between performance on the Digit Span tasks and Letter-Number Sequencing (LNS), a putative executive function working memory test. Compared to healthy subjects, the schizophrenia patients showed impairment in the medium effect size range on both DF (d=-0.55) and DB (d=-0.68). DB scores predicted LNS performance, whereas DF scores did not. Worse negative symptoms were associated with worse performance on DF, DB and LNS. These results do not reflect differential executive function working memory dysfunction in schizophrenia, but appear to support transient and executive function working memory as separable constructs.
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PMID:Transient and executive function working memory in schizophrenia. 1673

Dysfunction in the neuronal nicotinic acetylcholine receptor (nAChR) system has been implicated in the pathophysiology of schizophrenia, and it has been postulated that treatments that increase nAChR activity may improve symptoms of the disorder. We investigated the effects of the acetylcholinesterase inhibitor and allosteric nAChR modulator, galantamine, on cognitive performance and clinical symptoms when added to a stable antipsychotic medication regimen in nonsmoking outpatients with schizophrenia in a double-blind, placebo-controlled, parallel-group design. Participants were randomized to receive either galantamine (n=10) up to 32 mg/day or identical placebo (n=10) for 8 weeks and completed a cognitive battery at baseline and week 8 and clinical scales at baseline, week 4 and week 8. The primary outcome measure was attentional performance as measured by the d' measure in the Continuous Performance Test - Identical Pairs (CPT-IP) Version. Contrary to our hypothesis, galantamine treatment was associated with inferior performance on the CPT-IP, on the three-card Stroop task, and on the Letter-Number Span task without reordering. Galantamine had no effect on clinical symptoms. In summary, galantamine treatment, at a dose of 32 mg/day, was well tolerated but was not effective as an adjunctive treatment for cognitive deficits in stable nonsmokers with schizophrenia.
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PMID:High-dose galantamine augmentation inferior to placebo on attention, inhibitory control and working memory performance in nonsmokers with schizophrenia. 1832 40

Previous inconsistent findings concerning a link between working memory dysfunction and negative aspects of non-clinical schizotypy have been interpreted to cast doubt on the continuity model of 'negative psychosis-proneness'. This study employed the Letter-Number-Sequencing (LNS) task and the Trail-Making Test to assess more demanding, executive working memory. A secondary concern was to rule out possible mediating effects of familial schizophrenia. It was hypothesised that executive working memory impairment would be associated primarily with negative rather than positive schizotypy even in the absence of familial schizophrenia. Matrix reasoning controlled for IQ. In 87 university-student participants with no known family history of schizophrenia, lower LNS scores were associated with higher levels of negative and positive schizotypy traits. Counter to expectations, matrix reasoning scores were also associated with schizotypy, primarily the cognitive/perceptual traits. Results were similar when participants with a known family history of schizophrenia (10) were included (N=97). Findings support the view that impairment of executive working memory (indexed by LNS) is a reliable cognitive marker for negative (and perhaps also positive) schizophrenia vulnerability, independent of familial schizophrenia, and provide the first indication that some facets of IQ (e.g. inductive reasoning) might also be compromised in non-clinical schizotypy.
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PMID:Schizotypal traits impact upon executive working memory and aspects of IQ. 1842 12


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