Subjective fatigue, mental effort, and attention deficits after severe traumatic brain injury

Although fatigue is one of the most frequent complaints of individuals with traumatic brain injury (TBI), its mechanisms remain poorly understood. The objective of this study was to assess the relationships between subjective mental fatigue, mental effort, attention deficits, and mood after severe TBI.

and participants. A total of 27 patients with subacute/chronic severe TBI were compared with matched controls. Patients first rated their baseline subjective fatigue on the Fatigue Severity Scale (FSS) and on the Visual Analog Scale for Fatigue (VAS-F). Mood was assessed with the Montgomery and Asberg Depression Rating Scale (MADRS). Then, they performed a long-duration selective attention task, separated in 2 parts. Fatigue on the VAS-F was assessed again between the 2 parts and at the end of the attention task. Patients were also asked to rate on the VAS the level of subjective mental effort devoted to the task.

Patients reported a higher baseline fatigue than controls. They performed significantly poorer on the selective attention task. Significant correlations were found in the group with TBI between attention performance, mental effort, and subjective fatigue. Depression did not significantly correlate with fatigue.

These findings suggest that patients with more severe attention deficits have to produce higher levels of mental effort to manage a complex task, which may increase subjective fatigue, in line with the coping hypothesis.