Wisconsin Card Sorting Test: an indicator of vulnerability to schizophrenia?

The Wisconsin Card Sorting Test (WCST) is a neuropsychological test, hypothesized to be an indicator of dorsolateral prefrontal cortex (DLPFC) functioning. The performance of schizophrenic patients in our sample (off medication) was worse than the performance of healthy controls in all variables of the WCST, including perseverative responses (PR) as well as non-perseverative responses (NPR). The rate of perseverative and non-perseverative responses was neither a function of the severity of the illness (measured by SANS/SAPS scales) nor the duration of the disease. Healthy siblings of schizophrenic probands revealed more perseverative responses than healthy controls, but did not show any difference with respect to the non-perseverative responses. This finding suggests that the difficulty to shift a cognitive set, reflected by the frequency of perseverative responses, is in favor of the WCST as a vulnerability marker for schizophrenia, whereas non-perseverative responses presumably indicate a state, but not a trait marker of the disease. However, the usefulness of this indicator may be limited by its association with age, which is worthy of being studied in closer detail.