Chronic fatigue syndrome: intraindividual variability in cognitive functioning




Fuentes, Karina Yolanda

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Studies of cognitive performance among persons with chronic fatigue syndrome (CFS) have yielded largely inconsistent results. The present study sought to contribute to findings in this area by examining intraindividual variability as well as level of performance in cognitive functioning. A battery of cognitive measures was administered to 14 CFS patients and 16 healthy individuals on 10 weekly occasions. Analyses comparing the two groups in terms of level of performance as defined by latency and accuracy scores revealed that the CFS patients were slower in their reaction speeds than healthy persons. Comparing the groups with respect to intraindividual variability (as measured by intraindividual standard deviations and coefficients of variation) revealed greater intraindividual variability within the CFS group, although the results varied by task and time frame used. Intraindividual variability was found to be fairly stable across time, and consistent across tasks on each testing occasion. The present findings support the proposition that intraindividual variability is a meaningful correlate of cognitive performance in CFS patients.



Chronic fatigue syndrome