Stability and validity of memory-based subtypes of schizophrenia.

This study assessed whether verbal memory performance indexed by the California Verbal Learning Test (CVLT) can organize and reduce the heterogeneity of schizophrenia. The temporal stability, cognitive and clinical validity of: (a) a putatively cortical-subcortical-normative typology derived from dementia patients' scores on the CVLT and (b) a memory performance dichotomy based on a psychometric criterion and 1 CVLT summary score were evaluated. These memory subtypes were examined in 102 schizophrenia patients, 55 of whom were assessed again 3 years later. The results indicate that both methods yield potentially valuable illness distinctions on a cross-sectional basis, but fail to show truly trait-like properties. Furthermore, the evidence favors the validity of a parsimonious dichotomy over a more complex dementia-based typology.