Sports-Related Traumatic Brain Injury

Abstract

The speed and intensity of modern sports puts the athlete at risk for impacts to the head, or to the body when the impact force is transmitted to the head. Rapid head rotation caused by these impact forces may lead to a sports-related concussion (SRC), defined as a mild traumatic brain injury, typically resulting in short-lived disturbance of the central nervous system function. The diagnosis of SRC is clinical, although supported by sideline tests such as the Sports Concussion Assessment Tool (SCAT) - 5th Edition. At the time of SRC, the brain is highly vulnerable for additional impacts, and the concussed athlete must immediately be removed from the play. Following an initial 24–48 h period of brain rest, the athlete should then commence a graduated return-to-play protocol, meaning that following a SRC, full-contact sport cannot be initiated before a minimum of 6 days. The short- and long-term health effects of SRCs, particularly when repeated, are increasingly recognized. While the majority recover completely, persisting debilitating symptoms develop in a subset of concussed athletes. Post-concussion syndrome (PCS) is a poorly defined condition, which is most commonly described as more than three symptoms persisting for more than 3 months. Preferably, the term persisting post-concussive symptoms could be used. Regardless of terminology, persisting symptoms pose a number of therapeutic challenges. Repeated SRCs are also associated with depression, mild cognitive impairment, Parkinson’s disease, and an earlier onset of Alzheimer’s disease. Furthermore, some athletes attaining a high number of SRCs during their careers (e.g., boxers, American football and ice hockey players, and others) have been diagnosed with premature dementia, personality disorders, and Parkinsonism. At autopsy, an increased and irregular deposition of phosphorylated tau (p-tau) has been observed. Chronic traumatic encephalopathy (CTE), charachterized by these p-tau depositions, is a highly feared, yet controversial consequence of repeated SRC. In the near future, refined diagnostic tools, neuroimaging protocols, and biomarkers may improve the diagnostic accuracy of SRC and aid in the development of improved therapies.