A comparison of clustering solutions for cognitive heterogeneity in schizophrenia.

A cluster analytic solution based upon a battery of tests consisting of the Halstead Category and Tactual Performance Tests, the Trail Making Test, and the Wisconsin Card Sorting Test was compared with a solution based on the subtests of the Wechsler intelligence scales, utilizing a sample of 221 schizophrenic patients. Both analyses permitted four-cluster solutions, and we found a weak but significant degree of association between solutions. Examination of external validity of the two solutions revealed stronger associations with clinical variables for the Wechsler-scale-based solution. The major conclusions were that the existence of cognitive heterogeneity in schizophrenia exists across a broad range of abilities, and appears to reflect a combination of continuity of ability level and existence of possible subtypes requiring further neuropsychological and neurobiological verification.