Symptoms of schizophrenia and neurocognitive test performance.

Schizophrenic in-patients were rated on factor-derived symptom dimensions based on negative and positive symptom ratings. Participants were administered neuropsychological tests (digit span, digit vigilance, logical memory, and Trails A and B) and then instructed on how to improve performance on the tests. Follow-up tests were administered shortly after coaching. Comparisons of pre- and post-instruction test scores indicated that the patient group was able to improve significantly their performance on the tests after coaching. Symptom dimensions were predictive of improved post-instruction test performance beyond the impact of the level of pre-instruction scores. Symptoms of disorganization and negative symptoms were related to lack of ability to improve performance on one or more of the tests, and positive symptoms and premorbid adjustment were associated with improved post-instruction performance. The symptom dimensions provide a potentially useful approach to reducing heterogeneity within samples of schizophrenic patients.