| Abstract|| |
Aim: The present study attempted to find out the relationship between positive and negative clinical symptoms and Wisconsin Card Sorting Test (WCST) performance in a group of schizophrenia patients.
Methodology: Fifty schizophrenia patients were assessed using the Positive and Negative Syndrome Scale (PANSS) by a trained psychiatrist (TKA) and two groups, each of 25 positive symptom and 25 negative symptom schizophrenia patients were formed. On these fifty patients with schizophrenia and 15 normal control groups, WCST measures were applied by a clinical psychologist (SS) who remained blind to the PANSS score.
Results: Schizophrenia diagnosis significantly affects WCST performances. One-way analysis of variance (ANOVA) revealed schizophrenia patients showed a significant impairment on all WCST indices compared with normal subjects except versus total number of correct responses. Post hoc comparison (Tukey HSD Test) between means revealed that negative schizophrenia patients showed significantly worse performance on most WCST performance parameters: percent errors, perseverative responses, percent perseverative responses, perseverative errors, percent perseverative errors, and conceptual level responses.
Conclusions: Both positive and negative symptom schizophrenia patients have some distinct WCST measures deficits.
Keywords: Cognitive deficit, negative symptom, positive symptom, schizophrenia, Wisconsin Card Sorting Test
|How to cite this article:|
Singh S, Aich TK, Bhattarai R. Wisconsin Card Sorting Test performance impairment in schizophrenia: An Indian study report. Indian J Psychiatry 2017;59:88-93
| Introduction|| |
Cognitive impairment in schizophrenia has been reported across all cognitive domains.,, Three core cognitive functions commonly attracted a great deal of interest and appeared to have neurobiological significance for understanding of schizophrenia: attention, memory, and executive functions.,, Neuropsychological studies or cognitive tests' performances measuring primary frontal cortex functions are Wisconsin Card Sorting Test (WCST), Continuous Performance Test (CPT), trail making test and measures of verbal fluency, Tower of Hanoi test besides others described in literature.,,
WCST is the commonly and widely used neuropsychological test measures of executive function in terms of concept formation, planning and cognitive flexibility, visual spatial working memory, deductive reasoning, problem solving, and set shifting ability.,, Although schizophrenia patients have consistently been shown to perform worse than normal controls on the WCST, research relating WCST performance to symptom dimensions has produced inconsistent results. Many authors reported predominantly negative symptoms are related to poor performance.,, The relation of WCST performance to positive symptomatology is less clear, with inconsistent findings varying from better to worse performance on the WCST.,
Studies on WCST in schizophrenia patient population are rare from India. Hence, we tried to investigate this relationship between the WCST performance and schizophrenic illness with a specific emphasis on the positive and negative dichotomy.
| Methodology|| |
The study was conducted at the Central Institute of Psychiatry, Kanke, Ranchi, in the state of Jharkhand, India. Study sampling was purposive, comprised fifty schizophrenia patients, diagnosed according to the International Classification of Diseases, Tenth Edition (ICD-10), and fulfilling our inclusion and exclusion criteria. Inclusion criteria were male schizophrenia inpatients in the age group of 18–45 years and having a minimum education up to 8th standard. Exclusion criteria were evidence of organicity either from history or clinical examination, any comorbid major psychiatric disorder or mental retardation, any history of alcohol or drug dependence, being treated with electroconvulsive therapy in the preceding 12 months, and patients who did not give consent to participate in the study.
Fifteen age- and education-matched subjects, who were unrelated to the patients and did not have any history of substance abuse or mental illness, were taken up as control for the present study.
After taking the consent to participate in the study, an unstructured interview was conducted to collect personal information about the subject with the help of relatives as well as from the subjects himself. A specially designed sociodemographic and clinical data sheet were prepared to note down patients' age, level of education, occupation, age of onset of illness, total duration of illness, clinical diagnosis, etc., Diagnosis was confirmed according to the ICD-10 Diagnostic Criteria for Research.
A trained psychiatrist (TKA) rated these patients' psychopathology using Positive and Negative Syndrome Scale (PANSS) rating scale. The patients were placed in the “positive subtype” if they had a positive composite scale score valence and those with a negative valence were classified as “negative subtype.” Twenty-five positive symptom schizophrenia and 25 negative symptom schizophrenia patients were thus selected for the present study. WCST were applied by the trained clinical psychologist (SS) within 48 h of the administration of the PANSS. Clinical psychologist kept herself blind to the positive and negative subtype of our patient population till the completion of WCST performance. Before starting the test, the subjects were informed about the purpose of the study and the importance of cooperation in the study. Subjects were tested in a private quiet room. WCST was given to both the patients as well as to the control groups. Instruction, administration procedure, and scoring were taken from the WCST manuals. Item instructions were repeated or paraphrased as and when necessary to allow the client to understand.
WCST consists of four stimulus card and 128 response cards that depict figures of varying forms (crosses, circles, triangles, or stars), colors (red, blue, yellow, or green), and number of objects (one, two, three, or four) on them. As the task is usually administered, the four stimulus cards with the following characteristics are placed before the subject in left-to-right order: one red triangle, two green stars, three yellow crosses, and four blue circles. The subject is instructed to sort each response card under one of the stimulus cards, whichever he or she thinks is correct. After each sort, the subject is told whether the sort was right or wrong. The subject must discover the correct matching rule using this feedback (right or wrong). No other instructions are given throughout the test. The instructor begins by responding “right” each time the subject matches for color. This continues until ten consecutive cards have been sorted by color. The examiner then, without forewarning or comment, changes to “form” as the correct response. After ten consecutive forms' responses, the principle changes to “number” and so on. The test continues until either the subject has completed six categories or all 128 cards have been used.
Data thus obtained were subjected to descriptive statistics such as mean, standard deviation, and percentage profile, done to different demographic and clinical variables. One-way analysis of variance was performed to compare performance among positive and negative schizophrenia patients and normal control subjects. For multiple comparisons between groups, post hoc analysis with “Tukey's highly significant difference test” (Tukey HSD) was performed. For carrying out detail statistical analysis, computer-assisted statistical programme was used.
Description of tools
Positive and Negative Syndrome Scale
It includes thirty items, 18 items from the Brief Psychiatric Rating Scale and 12 items from Psychopathology Rating Scale. Each item is accompanied by a complete definition as well as detailed anchoring criteria in a 7-point format rating from 1 = absent to 7 = extreme. The PANSS includes a 7-item scale for positive symptoms, a 7-item scale for negative symptoms, and a 16-item scale covering general psychopathology. The rating of the PANSS provides summary scores on the positive scale, negative scale, general psychopathology scale, and a composite (positive minus negative) index.
Wisconsin Card Sorting Test
A detailed analysis of WCST performance includes as many as 15 different scores related to several parameters. Scores are generated on the total numbers of trials administered, total number of correct responses (the number of items that the examiner numbered during administration and that were not circled later), and total number of error responses (the number of items that have been circled).,
Assessor also noted the percent errors (total number of errors divided by number of trials administered). Perseverative responses, percent perseverative responses (total number of perseverative response divided by number of trials administered), perseverative errors (number of errors in which a subject continuously respond incorrectly using the same pattern), percent perseverative errors (reflect the density or concentration of perseverative error in relation to overall test performance), nonperseverative errors, percent nonperseverative errors are various scores generated related to subject's perseverative responses during the test.
Conceptual level responses (CLR: All consecutive correct responses including ambiguous correct responses that occurred in runs of three of more) and percent CLR (percentage of correct response occurring in runs of three or more) were also assessed during the test procedure. Assessment is also done on the number of categories completed, trials to complete first category, failure to maintain set (FTMS), and learning to learn (learning to learn reflects the client's average change in conceptual efficiency across the consecutive categories of the WCST).
| Results|| |
[Table 1] shows that there was no significant difference between the two schizophrenic subtypes on various demographic and clinical variables. [Table 1] also shows that normal control group did not differ on age and education, in respect to schizophrenic population.
[Table 2] shows average positive and negative symptom scored and the composite index score by the positive and negative schizophrenic groups.
Raw score means were calculated for the WCST variables that cannot be standardized. [Table 3] shows the results of one-way ANOVA and [Table 4] shows the post hoc comparison between means by diagnosis. Diagnosis significantly affects test performances: all the schizophrenia patients showed significant impairment on all the WCST indices compared with normal subjects except versus total number of correct responses (F = 2.1, DF = 2.7, P = nonsignificant). Mean profile configuration also shows it.
|Table 3: Comparison among positive schizophrenics, negative schizophrenics, and normal control in executive functions as measured by Wisconsin Card Sorting Test|
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|Table 4: The post hoc comparison (Tukey's highly significant difference test)|
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The post hoc comparison (Tukey HSD Test) between means revealed that negative schizophrenia patients showed significantly worse performance on the most WCST performance parameters: percent errors, perseverative responses, percent perseverative responses, perseverative errors, percent perseverative errors, and CLR. On nonperseverative errors, total number of trials administered and total number of correct responses, no significant difference was found between positive and negative schizophrenics [Table 4].
| Discussion|| |
Key neurocognitive deficits associated with impaired executive ability, believed to be mediated by the frontal lobes, are deficits in the ordering or handling of sequence, impairment in establishing or changing set, impairment in maintaining a set, decreased ability to monitor personal behavior, dissociation of knowledge from the direction of response and altered attitudes. Most commonly used executive function measure that assesses deficit in inhibitory control is WCST. Studies of WCST in schizophrenia patients have generally found significant impairments on performance of executive ability.,,,,
In the present study also, executive function deficits as measured by Wisconsin card sorting revealed that schizophrenia patients (henceforth will be mentioned as “schizophrenics”) performed poorer than normal control subjects (henceforth will mentioned as “normal”). On all the scoring area, it was found that there was statistically significant difference between “schizophrenics” and “normal” except on total number of correct responses [Table 3].
In WCST, total number of trials to successfully complete the first category and the number of CLR are linked to the degree of initial conceptualization and the capacity for abstraction. These cognitive abilities require the proper functioning of the frontal lobe. The CLR score is the total number of consecutive correct responses in a sequence of three or more. This definition is based on the principle that a subject succeeding on three consecutive trials is considered to have at least an intuition concerning the appropriate strategy for the sorting task at hand and that the correct sequence produced is not a result of random responding.
Our findings indicate that “schizophrenics” had taken more number of trials administered (F = 199.1, DF = 2.7, P<0.001) and had made more total number of errors (F = 534.4, DF = 2.7, P<0.001) and showed impaired CLR (F = 278.5, DF = 2.7, P<0.001) in comparison to “normal” [Table 3].
In our study on all parameters of perseveration: perseverative responses (F = 1592.0, DF = 2.7, P<0.001), percent perseverative responses (F = 1121.9, DF = 2.7, P<0.001), perseverative errors (F = 577.9, DF = 2.7, P<0.001), and percent perseverative errors (F = 1105.2, DF = 2.7, P<0.001), “schizophrenics” were found to be more deficient in relation to “normals.” Some investigators regard the number of perseverative errors as an most useful measure derived from the WCST., WCST perseverative errors have been interpreted as a failure to inhibit a learned response despite receiving error information and has been described as the cardinal feature of frontal lobe impairment.,
In our study on parameters of nonperseverative errors (F = 650.7, DF = 2.7, P<0.001) and percent nonperseverative errors (F = 354.6, DF = 2.7, P<0.001), “schizophrenics” were found to be more deficient in relation to “normals.” Nonperseverative errors occur when the subject incorrectly sorts the cards without perseverating on the wrong response. The number of nonperseverative errors is typically used as an indicator of nonfrontal cortical functioning.
The number of categories completed by schizophrenics was also found to be less than “normal” (F = 728.4, DF = 2.7, P<0.001) in our study. They also took significantly more number of trials to complete first category (F = 1538.0, DF = 2.7, P<0.001) than “normals.” The total number of categories achieved reflects overall success, whereas number of trials to complete the first category provides an index of conceptual ability.
The FTMS index is a measure of the loss of the correct sorting principle during testing. The FTMS sheds light on conceptual instability. This index also construed as a measure of working memory. The FTMS score is the number of sequences of five correct responses or more, followed by an error, before attaining the 10 necessary for a set change. Our schizophrenic patients also found to be deficient in “maintenance of set” irrespective of their prominence of positive or negative symptom presentation (F = 214.7, DF = 2.7, P<0.001). Because most of the patients had not completed three categories, so learning to learn was not scored and differences were not studied. In most of the studies, it has been found that schizophrenics had problem with the ability to get into the appropriate response set for a given task, to maintain the set, and to sift set as needed., According to Heaton, in 1981, failure to complete four stages may be considered as a good index of impaired functioning. The schizophrenics had taken more number of trials to complete the first categories in a report by Bellini et al. compared to “normals.”
In the present study, negative schizophrenics showed more impairment on most of the scoring area of the WCST as a measure of executive functions in comparison to positive schizophrenics and normals. Performance of negative schizophrenics was most impaired on perseverative errors, percent perseverative errors, perseverative response, and percent perseverative response. Few researchers in the past also reported that patients with higher negative score had more perseverative errors, perseverative responses, and completed fewer categories on the WCST., It is generally accepted that negative symptoms are associated with cognitive dysfunction of more complex nature.
However, our findings are not consistent with the notion that cognitive deficits are uniquely associated with negative symptoms. Instead, the result is in agreement with the suggestion of Green and Nuechterlein in 1999 that there may be specific cognitive correlation of both positive and negative symptom dimension. WCST impairment is said to be correlated with both negative and positive symptom dimension. Few published results suggest that the neuropsychological dysfunction in schizophrenia is present at the onset of the illness and is neither secondary to previous neuroleptic treatment nor secondary to chronicity of the illness. In CATIE trial, neurocognitive deficits at baseline were minimally correlated with negative symptom severity but essentially independent of positive symptom severity.,
| Conclusions|| |
The present study provides some evidence for the hypothesis that dimensions of schizophrenia symptoms may be distinctly related to neurocognitive function. Negative symptoms show associations with impaired performance on neuropsychological tests sensitive to frontal functioning. This interpretation is in agreement with the model of schizophrenia as proposed by Green and Nuechterlein, which states neurocognitive deficits are central to the chronic disabilities of patients with schizophrenia and relatively independent of symptomatic expressions of schizophrenia. Cognitive deficits and negative symptoms may both reflect a trait-like pathophysiology in schizophrenia. Finally, understanding cognitive impairment is important in the light of search for effective treatment for the same in schizophrenic patients. Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative began to identify effective treatment for cognitive impairment in schizophrenia or the “MATRICS” project, an interdisciplinary collaboration designed to support the development of pharmacologic agents to improve cognition in schizophrenia.
First, only single gender, i.e., “male patients,” was considered in the present study. Second, demographic variables, such as socioeconomic status religion and caste, were not controlled, which might have influenced the results of the study. Third, the severity of psychopathology was not taken into consideration, and finally, neuroleptic doses received by the patients were not controlled in the present study.
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Conflicts of interest
There are no conflicts of interest.
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Tapas Kumar Aich
BRD Medical College, Gorakhpur, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3], [Table 4]