Tower of Hanoi and WCST performance in schizophrenia: problem-solving capacity and clinical correlates.

We administered a computerized version of WCST, a well established test, sensitive to executive function deficits in schizophrenia that involves many features of cognitive processing, and of Tower of Hanoi, a test that may offer cognitive challenges more specifically related to planning and sequencing, to 28 schizophrenic patients and 28 matched controls to examine a worthwhile question regarding the relative ability of these two tasks to differentiate schizophrenia and normal groups as well as exploring the relationship of these two instruments to clinical variables. The schizophrenic patients performed significantly worse than normal subjects both on Tower of Hanoi test and on WCST. The discriminant analysis identified in a multivariate way a pattern of indexes that differentiate the two groups. This pattern, characterized by specific indexes of WCST and TOH, could suggest the existence of a common underlying factor that determines the cognitive impairment in problem-solving of schizophrenics. These findings and the relationship with positive and negative symptoms have been discussed in the light of the model of the impairment in the internal representation of context information.