Objectives: Various biological, psychological and social mechanisms have been shown to be associated with the development of subjective fatigue in different patient groups. There is currently a scarcity of longitudinal studies examining the mechanisms associated with fatigue following traumatic brain injury (TBI). The overall aim of the study is to examine trajectories and mechanisms associated with subjectively reported persistent fatigue within the first year following moderate to severe TBI. More precisely the study will: a) establish frequency and severity of persistent fatigue following moderate to severe TBI, b) investigate clinical subgroups based on symptom clusters, included trajectories of fatigue and related symptoms during the first year post-injury, and c) study the contribution of intraindividual pre- and co-morbid psychological mechanisms, such as premorbid fatigue, personality, somatic complaints, resilience, emotional distress, reward sensitivity and injury-related cognitive deficit, to the development of persistent fatigue. The latter aim includes an attempt to replicate and elaborate a model of fatigue following TBI proposed by Ponsford et al. (2015).
Methods: A representative sample of patients will be recruited in a prospective study design. The study inclusion started in January 2018, and will continue until the sample has reached a sufficient size to align with a priori power analyses, estimated to 125. Patients with moderate to severe TBI (Glasgow Coma Scale score 3-12 and/or radiologically confirmed intracranial injury), between the ages 18 and 65 living in Eastern Norway are included. Patients must have sufficient communicative and sensorimotor function to complete the study protocol. Exclusion criteria are premorbid neurological disorders ongoing substance abuse and psychiatric disorders. Follow-up assessments will be performed at six and twelve months post-injury. The self-report questionnaires Fatigue Severity Scale and Chalder Fatigue Scale are employed as primary outcome measures. The study further incorporates neuropsychological measures (IQ, sustained attention and executive functions), self-report measures (personality, resilience, behavioral inhibition/activation, optimism, loneliness, pain, mental and somatic health distress), blood parameters and injury characteristics, in order to achieve a broad approach to potentially contributing mechanisms.

Preliminary Results: Recruitment is ongoing, and a total of 55 patients have been included, of which 32 have completed the first follow-up. Preliminary descriptive results from the first follow-up is shown. 

Conclusion: The study aims to provide clinicians with knowledge about predispositional and maintaining mechanisms involved in persistent fatigue, which may be addressed in rehabilitation of patients with traumatic brain injury.

Persistent fatigue following moderate and severe TBI - a prospective longitudinal study