Cognitive inflexibility and pre-frontal dysfunction in schizophrenia and mania.

The ability to shift cognitive set, which is probably subserved, at least in part, by the pre-frontal cortex, was determined for schizophrenic, bipolar (manic) and control subjects, using the Wisconsin Card Sorting Test (WCST). The schizophrenic and manic subjects both demonstrated poor performance on the WCST, suggesting that cognitive inflexibility and/or pre-frontal dysfunction, is not specific to schizophrenia (although laterality differences could exist). Moderate levels of poor performance in the non-psychiatric control group suggest the need for a review of the cut-off figures in the WCST currently used for predicting 'brain damage' and 'focal frontal involvement', especially given the trend for the increasing use of cognitive assessment and rehabilitation in the major psychoses.