ABSTRACT
OBJECTIVE: Cognitive impairment is a common symptom of multiple sclerosis (MS). The present study aimed to assess fatigue-related diurnal variations of cognitive performance in MS patients. METHOD: Subjective cognitive fatigue and cognitive performance in three reaction time tasks differing in cognitive demands (alertness, Go/NoGo, divided attention) was measured at three different times of day on two consecutive days for MS patients, stroke patients, and healthy control participants. RESULTS: Objective measures of cognitive performance revealed poorer performance for both groups of patients than for controls. A diurnal decline of cognitive performance was only observed for the two groups of patients but not for healthy controls. This decline corresponded to the patients' subjective reports of increasing cognitive fatigue during the day. CONCLUSION: Cognitive fatigue in both MS and stroke patients is not only reflected in subjective ratings but also affects objectively measured performance in cognitive tasks.
