By S. Ahmad Sajjadi, MD, PhD, MRCP
In the recent issue of the Journal of the American Medical Association (JAMA), researchers from Boston University published seminal findings on the prevalence of chronic traumatic encephalopathy (CTE) in American football players. Understandably, the study has generated numerous headlines.
CTE is characterized by abnormal accumulation of a protein called tau in specific parts of the brain after repeated head trauma, leading to abnormal behavior, cognitive decline, or both. In the new study, the largest study of its kind, post mortem examination of the brains of 202 football players revealed a high prevalence of CTE among professional players (98.3%) and a much lower, although still significant, prevalence of CTE (21%, 3 of 14 players) in those who did not continue playing beyond high school. Despite a number of limitations that may result in an exaggerated risk estimate, the study confirms the notion that repeated head injury is an important risk factor for developing cognitive and behavioral impairments mediated by accumulation of abnormal tau protein later in life.
But what do we make of the result most relevant to the general public – the rates in those who only played high school football? For both the high school and the professional players, it is likely that the results represent an overestimation of the actual prevalence of CTE – the study had access primarily to brains of people who developed overt symptoms or suspicion of brain pathology. This, the lower occurrence of CTE compared to professionals, and the fact that each case was mild in severity, might be a reassuring sign suggesting that our kids will be safe engaging in contact sports. But until larger studies that include those with and without symptoms are available, it is difficult to reach a strong conclusion. What is clear, however, is that more study is needed and kids playing any sport should practice safety precautions, such as refraining from contact sports for a period following concussions.