Depression and sports-related concussion: A systematic review.

Context: Head injuries are risk factors for chronic depressive disorders, but this association remains poorly explored with regards to concussion.

Objectives: The objective of this review was to evaluate the incidence of depressive symptoms and depression after sports-related concussion. We also endeavored to identify the response elements regarding the pathophysiology of these symptoms.

Methods: A systematic search of PubMed and Embase was conducted focusing on papers published until 1st December, 2016, according to PRISMA criteria The following MESH terms were used: (concussion or traumatic brain injury) and sport and (depression or depressive disorder).

Results: A depressive disorder can appear immediately after a concussion: depressive symptoms seem to be associated with the symptoms of the concussion itself. A depressive disorder can also appear later, and is often linked to the frequency and number of concussions. Furthermore, the existence of a mood disorder prior to a concussion can contribute to the onset of a depressive disorder after a concussion.

Limits: There is an overall limit concerning the definition of a depressive disorder. In addition, when these studies had controls, they were often compared to high-level athletes; yet, practicing sport regularly is a protective factor against mood pathologies.

Conclusions: Depressive symptoms after a concussion seem to be associated with postconcussion symptoms. Repeat concussions can contribute to later-onset major depressive disorders. However, playing sports can protect against major depressive disorders: thus, it is essential to evaluate concussions as accurately as possible.