The effects of post-traumatic depression on cognition, pain, fatigue, and headache after moderate-to-severe traumatic brain injury: a thematic review

Background: Post-traumatic depression (PTD) is one of the most common secondary complications to develop after moderate-to-severe traumatic brain injury (TBI). However, it rarely manifests singularly, and often co-occurs with other common TBI impairments. Objective: The objective of this thematic review is to evaluate studies examining the relationships between PTD and cognition, fatigue, pain, and headache among individuals with moderate-to-severe TBI. Results: We reviewed 16 studies examining the relationship between PTD and cognition (five articles), fatigue (five articles), pain (four articles), and headache (two articles). Two studies failed to identify the significant associations between PTD and neuropsychological test performance, while one study found a positive association. Two other studies found that early PTD was associated with later executive dysfunction. Studies on fatigue suggest it is a cause, not consequence, of PTD. Individuals with PTD tended to report more pain than those without PTD. Studies examining relationships between PTD and post-traumatic headache were equivocal. Conclusions: Studies evaluating the effects of PTD on common TBI impairments have yielded mixed results. Evidence suggests PTD precedes the development of executive dysfunction, and a strong link exists between fatigue and PTD, with fatigue preceding PTD. Future prospective studies evaluating PTD relationships to pain and headache are warranted to elucidate causality.