Response variability is associated with self-reported cognitive fatigue in multiple sclerosis.

Cognitive fatigue is a common, often debilitating symptom of multiple sclerosis (MS). Although MS patients frequently report that fatigue negatively affects cognitive functioning, most studies have found little evidence for a direct relationship between self-reported cognitive fatigue and traditional measures of neuropsychological functioning. The purpose of the present study was to examine the association between self-reported cognitive fatigue and a measure of response time variability (RTV). MS patients demonstrated significantly higher RTV than controls, and RTV was highly correlated with self-reported cognitive fatigue among relapsing-remitting and secondary progressive MS patients. Results highlight the need to implement newer methods to further elucidate the relationship between cognitive fatigue and neuropsychological functioning in MS. Copyright 2009 APA, all rights reserved.