Ji. Tracy et al., TRANSIENT FLUCTUATIONS IN COGNITIVE-FUNCTIONING IN SCHIZOPHRENIA BASED ON SINGLE-CASE STUDY METHODS, Schizophrenia research, 17(2), 1995, pp. 201-209
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.