Mental fatigue after traumatic brain injury: Exploring different determinants across severity levels.

Fatigue is a frequent complaint after traumatic brain injury (TBI), irrespective of severity. We aimed to identify factors contributing to mental fatigue in various severities of TBI. This retrospective study examined fatigue, information processing speed, coping, and emotional distress in individuals with mild TBI (n = 56), moderate-severe TBI (n = 25), and healthy controls (n = 30). The aim was to assess differences in information processing speed between patients and controls and, within the patient groups, to explore how information processing speed, coping, and emotional distress relate to mental and physical fatigue. Slower information processing was correlated with higher mental fatigue (.40 to .50) in the moderate-severe TBI group. For moderate-severe TBI, depression and passive coping positively correlated with mental fatigue (.42 and .51). For mild TBI, depression, passive coping and anxiety positively correlated with mental and physical fatigue (.38 to .53). To conclude, slower information processing in moderate-severe TBI is likely to pose a higher cognitive load in demanding (task) situations, which in turn relates to higher levels of mental fatigue. In contrast, mental fatigue after mild TBI seems mainly associated with mental distress and passive coping. The results underscore the importance of considering injury severity when evaluating fatigue and tailoring clinical interventions.