Sports Concussion Expert Witness Explains Long Term Concussion Risk in Youth


By Vernon B. Williams, MD

Commitment. Hard Work. Sportsmanship. Physical Fitness. Time Management. Teamwork. Scholarship Opportunities. Self Confidence. These are often cited and well-recognized benefits of and lessons learned through participation in youth sports. One of the most pressing concern over participation in youth sports is related to the risk of long-term consequences from concussion. A rising tide of personal opinion has been reported in the media, with many calling for significant restrictions if not outright ban of youth participation in some contact and collision sports. Some of the most frequently cited reasons for concern are as follows:

  • There is now an improved understanding of concussion epidemiology. Not too long ago, concussion rates in the United States were typically reported at about 300,000/year. More recent CDC data suggest concussions are far more common, occurring at rates of 1.6 – 3.8 million/year. Concussion has transitioned from an unrecognized epidemic to a well-understood risk of athletic competition.
  • There has been an explosion of published data in scientific literature and publicized accounts in the lay media on the topic of concussion in sports. Some of those data show the potential for problems in retired professional athletes. Increased rates of depression and cognitive impairment in retired players has been suggested by way of survey data from the Center for the Study of Retired Athletes and The University of Michigan Institute for Social Research
  • Technology is enabling recognition of abnormalities on neuropsychological tests and advanced imaging studies, even in the absence of symptoms or ability to identify deficits on physical examination. This gives rise to consideration of concussion as more than just a transient functional deficit and the possibility of sub-concussive events having a role in neurologic function.
  • Although chronic traumatic brain injury has been described in boxers since the late 1920’s, work looking at genotype and duration of exposure provided more information on the risks of repetitive brain trauma in retired boxers. Most recently, neuropathologic studies on the brains of retired professional football players and other athletes who suffered multiple concussions found evidence of Chronic Traumatic Encephalopathy (CTE). There appears to be a latency period (of varying duration) between the exposure to concussive head injury and later development of signs and symptoms.

Millions of youth and adolescent athletes are at risk for and suffer concussion while participating in sports activities. Evidence of depression and dementia after years of participation in professional sports, and evidence of abnormalities on imaging after concussion or repeated impact have naturally resulted in a groundswell of concern. There are questions of clinical, and cultural significance. What are the risks of long-term consequences of concussion from participation in youth sports? Will Pop Warner, AYSO, National Youth Hockey, AAU or other youth, adolescent and club sports activities put an individual at significant risk for chronic post-concussion syndrome? Or prevent acceptance and enrollment at a prestigious academic institution? Is brain damage a consequence of youth sports? Are there academic consequences? These and other questions are being posed and answers are being pursued through a number of initiatives, both large and small. But what is the state of the science at present?

Review of the current literature reveals that while there is cause for concern, the existing evidence for long-term risk after concussion in youth sports is mixed. Some studies suggest possible affect, but many find no significant or increase risk. A recent evidence-based guideline published by the American Academy of Neurology (AAN) finds that prior concussion is highly likely to be a risk factor for chronic neurobehavioral impairment across a broad range of professional sports (football, soccer, boxing, and horse racing) and there appears to be a relationship with increasing exposure. This so-called “dose response” (increased risk with increased exposure) is of particular interest. However, it is critical to understand that this evidence of risk is related to an individual having participated in professional sports. The AAN guideline goes on to state that data are insufficient to determine whether prior concussion exposure is associated with chronic cognitive impairment in amateur athletes.

Other recently published consensus and position statements from the Zurich Consensus Conference on Concussion in Sport and from the American Medical Society for Sports Medicine acknowledge increasing concern, but call for more large scale epidemiological studies to more clearly define risk and causation. All of the recently published documents provide detailed recommendations regarding current understanding of sports concussion, and recommendations for evaluation and management. None call for prohibition from participation in youth sports over concern for long-term consequences from concussion.

Fortunately, sport concussions appear to be self-limited and seem to typically resolve without any post-concussion syndrome or long-term consequences. There is likely a combination of known and as yet unknown factors that contribute to an individual’s risk for long-term consequences. Genetic predisposition, concussion frequency, total number of concussive episodes, sub-concussive event load, duration of exposure, medical and neurologic or neurobehavioral comorbidities, and other considerations may be risk factors and/or modifiers affecting long term consequences from concussion in youth athletes. Youth and adolescent athletes who have a history of multiple concussions and concerning or ongoing symptoms should seek guidance from a health care provider with experience and expertise in concussion management. Pre-participation counseling can assist athletes and parents as well as school and sports league officials. Neurologic examination, neuropsychological testing and advanced neuroimaging may assist those with specific concerns in making decisions regarding participation. It can be argued that in many respects, improved understanding of concussion, new rules, policies, guidelines, and management techniques, make sports participation safer than ever. The concern for risk should be balanced with awareness of the current state of understanding and the known benefits of sports participation.

About the Author: Vernon B. Williams, MD is a Sports Neurologist and Pain Medicine Physician. He is the Founding Director, Center for Sports Neurology at the Kerlan-Jobe Orthopedic Clinic in Los Angeles, California, the Director of Pain Medicine at the Kerlan-Jobe Orthopedic Clinic, the Founding Director of the Sports Neurology Fellowship at the Kerlan-Jobe Center for Sports Neurology and the Chief Medical Officer of the Sports Concussion Institute. Dr. Williams serves as consultant to the Los Angeles Lakers, Los Angeles Dodgers, Los Angeles Kings, Los Angeles Sparks, Anaheim Ducks, Loyola University, Fullerton College, and numerous high schools. He completed his Pain Medicine Fellowship at Johns Hopkins. He is a frequent speaker on sports neurology, concussion, and pain. Dr. Williams is an experienced expert witness and independent medical examiner.