Is the incidence of depressive disorders increased following cerebral concussion?

yes, in some populations. Youth and adolescents with self-reported history of concussion had increased risk of depressive disorders (strength of recommendation [SOR]: B, based on a prospective cohort study and a retrospective cohort study). Evidence was inconsistent for college athletes. Athletes with ≥ 3 concussions exhibited more depressive disorders, but no association was observed for those with 1 or 2 concussions compared to nonconcussion injuries (SOR: B, based on a cross-sectional study, a small prospective cohort study, and a casecontrol study). In semiprofessional and professional athletes, evidence was variable and may be sport related. Retired rugby players with a history of concussion showed no increase in depression compared to controls with no concussion history (SOR: B, based on a case-control study). Retired football players with previous concussions displayed increased incidence of depression, especially after ≥ 3 concussions (SOR: B, based on a prospective cohort study and a small case-control study). There is a significant risk of bias in these studies because of their reliance on self-reported concussions, differing definitions of depression, and possible unmeasured confounders in the study designs, making a causative relationship between concussion and depression unclear. ONLINE EXCLUSIVE