Genetics May Make Concussion Recovery More Difficult
When you experience a concussion, few things are certain. You are likely, but not guaranteed to experience a number of symptoms, and they may come on immediately or develop over the course of a few days. Adding even more uncertainty to the mix, the time it takes to recover from a concussion can take anywhere from a handful of days to months.
While the length of time it takes to recover from a brain injury is partly related to the severity of the injury, there is evidence a number of other factors are also involved. Now, research from Penn State indicates genetics may be one of those factors.
Peter Arnett, Professor of Psychology and Director of Clinical Training at Penn State, has observed hundreds of concussed athletes over the last ten years, which has culminated in the most research to find out why some people recover more quickly than others.
Arnett says the relationship between genetic factors and outcomes following brain injury has recently been receiving more attention, but little research has been devoted to exploring how specific genes influence concussion recovery. “We wanted to determine how the apolipoprotein E (APOE) gene influences symptoms following a sports-relation concussion.”
For the study, published in the Journal of the International Neuropsychological Society, Arnett and his team evaluated 42 collegiate athletes who had completed concussion testing within three months of their injury. The report says all the athletes had experienced a mild concussion, as diagnosed by team physicians, and underwent testing as soon as possible following the injury.
The players had their cheeks swabbed to provide DBA samples which were analyzed at Penn State’s Genomics Core Facility to determine the make-up of their APOE genotype.
In the report, Arnett explains there are three distinct versions of the APOE gene, known as alleles.
“The major alleles are called e2, e3, and e4. For this study, we focused on the e4 allele and how it influences concussion symptoms, as it is associated with unfavorable outcomes following brain injury.”
The team of researchers found that approximately one-third of the athletes tested had the e4 allele. Arnett told Penn State News, “I was a bit surprised by the high percentage, as we approximate 20 to 25 percent of the general population has the e4 allele.”
From there, the team compared the concussed athletes with the e4 allele against those without it, and found the athletes with that specific allele also showed worse outcomes as measured by the Post Concussion Symptom Scale (PCSS).
The PCSS, administered through the ImPACT computer program, surveys symptoms such as dizziness, headaches, nausea and other commonly experienced post-concussion symptoms to determine their severity.
“Athletes were able to rate their current symptoms from zero — representing no symptoms, to six — representing severe symptoms,” said Victoria Merritt, a doctoral candidate in Arnett’s lab and lead author on the study. “Athletes with the e4 allele reported greater physical and cognitive symptoms than athletes without it.”
Arnett said this is the first study to directly examine and establish a link between the e4 allele and post-concussion symptoms. “Our results overwhelmingly indicate that e4 positive participants may be at a greater risk for experiencing post-concussion symptoms.”
The researchers say they hope to expand on their findings in future studies by evaluating middle and high school students. Their goal is to help improve screening for athletes and military personnel who experience brain injuries.