Is there evidence for a relationship between cognitive impairment and fatigue after acquired brain injury : a systematic review and meta-analysis

Purpose: Fatigue is a major symptom of ABI. Greater fatigue is associated with cognitive impairment. Our aim was to systematically review, describe and analyse the literature on the extent of this relationship. Methods: Five databases were searched from inception. Studies were included where: participants had a defined clinical diagnosis of ABI which included TBI, stroke or subarachnoid haemorrhage; a fatigue measure was included; at least one objective cognitive measure was used. Three reviewers individually identified studies and determined quality using the Quality Assessment Tool for Observational Cohort and Cross-sectional Studies. Results: Sixteen of the 412 identified studies, investigating the relationship between cognitive dysfunction and fatigue, comprising a total of 1,745 participants, were included. Quality ranged from fair to good. Meta-analysis found fatigue was significantly associated with an overall pattern of cognitive slowing on tasks of sustained attention. A narrative synthesis found weak associations with fatigue and information processing, attention, memory and executive function. Conclusion: Analysis found sustained attentional performance had stronger associations with fatigue after ABI. Whereas, weak associations were found between fatigue and information processing, attention and to some extent memory and executive function. More focused research on specific cognitive domains is needed to understand the mechanisms of fatigue