TRANSIENT FLUCTUATIONS IN COGNITIVE-FUNCTIONING IN SCHIZOPHRENIA BASED ON SINGLE-CASE STUDY METHODS

The stability of cognitive performance in four schizophrenia patients was examined over st short time period. A cognitive battery highly sen sitive to organismic state (the Repeatable Cognitive-Perceptual-Motor Battery, RCPM) was utilized. Single-case statistical methods tested fo r within-individual change across five assessments at two week interva ls. All four subjects showed statistically significant post-baseline v ariation in a global measure of impairment (average impairment rating score) and in at least 50% of the individual tests having adequate tes t-retest reliability. Data are interpreted as providing suggestive evi dence of transient fluctuations in performance within a stable window of impaired cognitive functioning. These fluctuations appear substanti al enough to influence both research and clinical outcomes. The benefi ts of the single-case methodology employed are discussed. The data sug gest that significant transient fluctuations in cognitive performance can be observed in schizophrenia in domains purported to represent vul nerability markers of the disorder. The importance of accounting for t hese transient fluctuations in the attempt to identify enduring, trait -like characteristics of cognitive functioning in schizophrenia is dis cussed.