Schizophrenia, training paradigms, and the Wisconsin Card Sorting Test redux

The question of whether and to what extent poor performance on the Wisconsin Card Sorting Test (WCST) in patients with schizophrenia can be improved with coaching has been controversial. We review relevant studies with particular reference to the following issues: (1) can improvement occur? (2) if improvement does occur, what is its significance? and (3) what is the association between performance and neurophysiology? The studies indicate that in patients with schizophrenia performance can frequently be improved, but usually remains in the abnormal range. Similar results for memory measures have been reported in patients with amnesias or dementias of known neurological origin. This suggests that simple dichotomies between neurologic and psychological explanations of cognitive impairment and potential amelioration of such impairment may be inadequate. Comparisons of the results of studies using the WCST as a clinical tool with binary cut-off scores to define normal and abnormal, as a measure of neuropsychological function along a continuum, and as an activation stimulus to probe neurophysiology suggest that absolute WCST scores may not always accurately gauge the functional integrity of neural systems dedicated to the task. This situation may arise because of individual differences in endowment and in the capacity for neuronal compensation, as well as measurement error. Given these issues, caution is advised in the interpretation of WCST scores, which are best understood as representing a final common cognitive pathway that can be the product of diverse psychological, physiological, and neuroanatomic mechanisms.