Although football remains one of America's favorite spectator sports--even when a pandemic relegates many viewers to their televisions -- there's been a growing realization over the past decade of the hazards of the game for the players, in particular the risk of concussion.
Some professional players who experienced multiple concussions during their career were subsequently found to develop a degenerative disease called chronic traumatic encephalopathy or CTE, which can cause memory loss, confusion and progressive dementia. Much research has been devoted to learning how to prevent concussion and to help the brain heal after injury.
Recently Stanford researchers, including developmental biologist Stuart Kim, PhD, and sports medicine specialist Geoffrey Abrams, MD, conducted what's known as a genome-wide association study to identify genes involved in concussion risk. They published their findings recently in Medicine and Science in Sports and Exercise.
The researchers combed the medical records of nearly 300,000 people in the Bay Area and the United Kingdom to conduct the study. Over 4,000 of these people had a documented case of concussion. The scientists compared the genome sequences of those with a concussion with those without, in the hopes of identifying genes that might raise a carrier's risk of concussion.
A concussion is a brain injury that occurs when a blow or jolt to the head or body causes the head or brain to move quickly back and forth. It can cause short-term neurological symptoms including dizziness, nausea, headache or difficulty concentrating. Although most symptoms resolve spontaneously, it is important to consult a health care provider when a concussion is suspected.
Unlike previous studies of the genetics of concussion, in which researchers searched for links to specific subsets of target genes, screening the entire genome offers an unbiased way to look for links between genes and concussion.
"We screened the entire genome and were able to identify two genes that were associated with concussion," Kim said. "Most people have normal versions of these genes, but about 1% of the population have differences, or variants, that indicate they may be at increased risk."
The genes, SPATA5 and PLXNA4, are intriguing. PLXNA4 is a well-known gene in neurobiology research. It encodes a protein that is important during neurodevelopment by helping neurons make connections within the brain, and variants in the gene have been previously associated with an increased risk for Alzheimer's disease. And people with a deletion of SPATA5 are severely intellectually disabled, with hearing loss and vision impairment.
"When you have a concussion, you can experience visual and auditory disturbances," Kim said. "These are the same systems affected in people with a SPATA5 deletion. So now we have a possible mechanistic link between what is known from mainstream neurobiology research and concussion. No one would have guessed this link before this study, but the findings make sense."
Kim and Abrams are eager to study whether it's possible to predict which athletes or members of the military are likely to be at higher risk of concussion, and to implement interventions prior to injury such as targeted neck muscle strengthening or the use of specially designed protective equipment such as helmets or headbands.
"If we are able to clinically identify people at increased risk for concussion based on an underlying genetic predisposition, this has the potential to alter current prevention and treatment paradigms," Abrams said.