Efficacy of wisconsin card sorting test in cognitive remediation among patients with schizophenia: A randomized double blind controlled study

Last registered on November 21, 2022


Trial Information

General Information

Efficacy of wisconsin card sorting test in cognitive remediation among patients with schizophenia: A randomized double blind controlled study
Initial registration date
March 25, 2022

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
March 28, 2022, 7:11 AM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Last updated
November 21, 2022, 12:21 AM EST

Last updated is the most recent time when changes to the trial's registration were published.



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Other Primary Investigator(s)

Additional Trial Information

Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
The neurocognitive deficits is a disabling dimension of schizophrenia, with increasing recognition for psychosocial remediation approaches for this domain. WCST retraining by different instructional methods has provided variable results related to its beneficial/ generalizability effects on the other non-trained cognitive performances. The present study was intended to evaluate the efficacy of WCST retraining through the didactic retraining method on the performance of other non-trained neuropsychological tests of executive functions among patients with schizophrenia.
Methods: The present study was a randomised, double-blind controlled study conducted over 24-months among 60 patients with schizophrenia fulfilling the inclusion and the exclusion criteria. At baseline, the patients were administered with Number Back (N 1- and 2-Back) Verbal test, the Eysenck Series of Digit Span Test (ESDST), and the trail making test (TMT) to measure the baseline deficits in the various outcome measures, along with the PANSS (for illness severity) and the GAF (for global functioning). The patients were randomised equally into the control group (to receive treatment as usual ‘TAU’) or the experimental group (‘TAU’ and the intervention of WCST retraining (till they were error-free). After completing the WCST retraining, the various outcome measures were again administered to observe the changes in the different cognitive domains, the illness severity and the global functioning.
Results: Out of the 60 enrolled patients, with finally 30 patients in either group. At baseline, both the groups were homogenous with regard to the various socio-demographic, clinical, and outcome parameters. Compared to the control group in the experimental group, following WCST retraining, there was a significantly better improvement in the Hits score of N 1-Back (p=0.035), N 2-Back (p=0.045), digit forward score of ESDST (P=0.040), and the time to complete (p=0.033), and the number of errors in Set-A of TMT (p=0.029) respectively, without any significant changes in the PANSS and GAF scores. A positive correlation was found between the age of the patient and duration of education with performance on various cognitive performances including WCST parameters
Conclusions: WCST retraining of patients with schizophrenia resulted in significant improvement in the verbal working memory, attention and concentration, planning and sequencing domains of cognitive functions, but had no beneficial effect on the disease severity or global functioning.
Keywords: Schizophrenia, Cognitive deficits, WCST, N-Back test, ESDST, TMT, PANSS, GAF
External Link(s)

Registration Citation

Mishra, Sayali. 2022. "Efficacy of wisconsin card sorting test in cognitive remediation among patients with schizophenia: A randomized double blind controlled study." AEA RCT Registry. November 21. https://doi.org/10.1257/rct.9139-1.2
Experimental Details


administering the 128-card version of WCST. The test required the patients to match a series of cards beneath four reference cards according to shape, colour, and the number of geometric shapes and infer the sorting rule from feedback to their responses. The results were scored using the WCST: Computer Version 3: Research Edition (WCST: CV-3). The Didactic method was used for the purpose of WCST retraining till they were error-free. Didactic Method of WCST Retraining: The retraining was conducted on cards 1 to 5 and repeated for cards 32 to 37 adjusting for the correct sorting rule, so participants received 2 sets of training per 64-card deck. If the participant did not understand the concept even after training, the examiner was allowed to provide the following corrective steps: (a) explain the concept of number, (b) rephrase by explaining that only one principle is correct at a time, (c) explain that choosing the correct category again would be correct, and (d) explain that if the response is “Wrong”, it is probably true that it will continue to be wrong and he/she should try either shape or number. However, if after two sets of training (cards 1 to 5 and 32 to 37) the participant was still unable to correctly respond, the test was discontinued . The total Duration of intervention is 24 months. In the Control group: The control group was kept waitlisted and continued to receive the treatment as usual as per the hospital.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
N-Back (1 and 2-Back) scores, EDST scores, Trail Making Test scores
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Schizophenia runs a chronic debiliating course with relatively stable neurocognitive deficits. The neurocognitive deficits are reportedly in the range between 1.5 to 2.0 standard deviation below the healthy controls on several dimensions of cognition, especially verbal memory, working memory, motor speed, attention, executive function and verbal fluency. The neurocognitive deficits have a direct impact on the functional outcomes of the patients with schizophrenia including skills acquisition, problem solving and community living and predicts a poor prognosis. Thus, methods of cognitive remidiation are needed for improvement of the patient clinical condition and reduction of overall disease burden of schizophrenia .In view of limited evidence of pharmacotherapies in neurocogitive deficts in schizophrenia, studies have focussed on various psychological methods for cognitive remediation. Few previous studies have shown the Winconsin card sorting test (WCST) to be an useful tool for cognitive retraining in patients with schizophrenia. The WCST is primarily a test for measuring conceptual flexibility and problem solving, and is hypothesised to tap into the skills mediated by prefrontal cortical structures. Significant improvements in cognitve abilities was achieved by cognitive remidiation on WCST using different reinforcement and instructional techniques like self monitoring, scaffolding, and step-by-step didactic method of instructions. The didactic method of remediation has provided the most convincing evidence for improving the WCST performance. Furthermore, studies have found that such training has resulted in transfer (generalisation) of the learned skills to non-trained tests of executive functioning.The present study intends to evaluate the efficacy of cognitve remediation on WCST by step-by-step didactic method among patients with schizophrenia in a tertiary care center in India over 14 months. After enrollment, the patients with schizophrenia fulfilling the inclusion and exclusion criteria, will be randomized into 2 equal groups: the control group receiving the treatment as usual (TAU) of the hospital and the experimental group receiving WCST retraining till error free in addition to the TAU. The outcome measures assessing any change in the cognitive functions and overall disease severity following the intervention will be compared within and between the groups for any statistical significance.
Experimental Design Details
Randomization Method
Stratified randomization
Randomization Unit
Stratified randomization, Alternation, Double Blind Double Dummy
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

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