Neuropsychological heterogeneity in schizophrenia: a consideration of abstraction and problem-solving abilities.

The study examines heterogeneity in abstraction and problem-solving abilities among schizophrenic patients through a cluster analysis of scores from the Halstead Category Test, the Tactual Performance Test, Part B of the Trail Making Test and the Wisconsin Card Sorting Test obtained from 136 male schizophrenic inpatients. Extensive heterogeneity was noted among the five clusters extracted, marked by differences in both level and pattern of performance. Efforts were made to find associations between cluster membership and age, education, general intelligence, neurological comorbidity, and medication status. Such associations were noted in all cases, but the role of medication was viewed as equivocal. It was concluded that (i) there is extensive heterogeneity in both pattern and level of performance of schizophrenics on tests of abstraction and problem solving; and (ii) Some, but not all of this heterogeneity is associated with variations in age, education, general intelligence, and neurological comorbidity.