Objective measurement of fatigue following traumatic brain injury

OBJECTIVES: To quantify posttraumatic brain injury (post-TBI) mental fatigue objectively by documenting changes in performance on neuropsychological tests as a result of sustained mental effort and to examine the relationship between objectively measured mental fatigue and self-reported situational and day-to-day fatigue. PARTICIPANTS: The study included 202 community-dwelling individuals with mild-severe TBI and 73 noninjured controls. MEASURES: Measures included Cambridge Neuropsychological Test Automated Battery, Global Fatigue Index, and situational fatigue rating. METHOD: Subjects were administered a 30-minute computerized neuropsychological test battery 3 times. The second and third administrations of the battery were separated by approximately 2 hours of interviews and administration of self-report measures. RESULTS: The neuropsychological test scores were factor analyzed, yielding 3 subscales: speed, accuracy, and executive function. Situational fatigue and day-to-day fatigue were significantly higher in individual with TBI group than in individuals without TBI and were associated with speed subscale scores. Individuals with TBI evidenced a significant decline in performance on the accuracy subscale score. These declines in performance related to sustained mental effort were not associated with subjective fatigue in the TBI group. While practice effects on the speed and accuracy scores were observed in non-brain-injured individuals, they were not evidenced in individuals with TBI. CONCLUSIONS: Findings were largely consistent with previous literature and indicated that while subjective fatigue is associated with poor performance in individuals with TBI, it is not associated with objective decline in performance of mental tasks.