David J. Schretlen, PhD
The M-WCST is a modification of the original Wisconsin Card Sorting Test that eliminates all cards from the original 128-card deck that share more than one attribute with a stimulus card (e.g. each response card whose stimuli match a stimulus card in both color and form was eliminated). This results in a 48-card deck, which is used along with four stimulus cards. This and other modifications enable impaired and elderly adults to more easily understand the directions, reducing frustration. Age-, sex-, and education-based norms are provided in the Manual.
Four scores are calculated for the M-WCST: Number of Categories Correct, Number of Perseverative Errors, Number of Total Errors and Percent of Perseverative Errors. In addition, an Executive Function Composite score may be calculated.
- The M-WCST is highly sensitive to executive dysfunction in schizophrenia, with an effect size (Cohen's d) of approximately 1.1. This marginally exceeds that shown by the original WCST.
- The M-WCST shows excellent sensitivity to impaired problem solving and perseverative reasoning in individuals with many other neurological conditions, including Parkinson's disease, Huntington's disease, systemic sclerosis (scleroderma), left temporal lobe epilepsy, chronic alcoholism, Korsakoff's syndrome, subcortical vascular dementia, and mild cognitive impairment.
- The M-WCST has been found to detect executive deficits in individuals with bipolar disorder and major depression and in individuals genetically at risk of developing schizophrenia.
- In a study that compared patients with unilateral lesions with healthy controls, the Number of Categories Correct score was able to distinguish the clinical sample from the healthy controls. In addition, both the Number of Categories Correct score and the Number of Perseverative Errors score have been found to distinguish patients with Alzheimer's-type dementia from healthy elderly adults.
Advantages of Using the M-WCST
- The M-WCST takes less time to administer than the WCST and may be scored in just 2-3 minutes.
- The M-WCST eliminates the illogical possibility of scoring correct responses as perseverative errors-all perseverative responses are classified as errors.
- The M-WCST was co-normed with the tests normed by the Calibrated Neuropsychological Normative System (CNNS); 327 healthy participants made up the standardisation sample.
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