Last year, college football player Kosta Karageorge committed suicide, with his last text sent to his mother was “Sorry if I am an embarrassment, but these concussions have my head all [messed] up.” Two years prior, NFL player Junior Seau committed suicide via chest wound, leaving his brain to be studied by the National Institutes of Health – and ultimately finding damage to his brain.
While we are more aware than ever of concussions as a major threat to mental health, testing for concussions, especially mild ones, is still lagging. Neuroscience research is starting to reveal new ways to diagnose concussions, even absent the telltale behavioral symptoms.
According to the CDC, sports-related injuries are only a portion of what causes concussions. Falls, being struck by an object, and car accidents are among the leading causes for concussions in the US. For people between ages 15 and 44, car accidents are actually the leading cause of concussions.
Concussions occur when there is an impact to your head, leading to a difference in how your brain functions. These differences can relate to difficulties in balance, memory, and attention. Concussions can vary from unnoticeable to hospitalizing. Many people who have a concussion will probably not even know they had a concussion and will recover fully. For people who play sports or are involved in activities where head impact is common, quick locker room or sideline protocols only assess the most severe (grade 3) concussion symptoms – generally leaving out the mild (grade 1) or moderate (grade 2) concussions. Yet even the least severe concussions affect neural activity.
At Utah State University’s Learning, Education, & Auditory Processing (LEAP) Brain Imaging Laboratory, my colleagues and I, led by Ron Gillam, have begun to study the short-term effects of concussions using functional near-infrared spectroscopy (fNIRS). Although the data are preliminary, the findings are striking: showing greatly increased brain activity following a mild traumatic brain injury (mTBI).
How we came into this line of study was by chance. Gillam’s lab was initially piloting an fNIRS study on attention and memory using healthy adult participants in which participants performed two cognitive tasks: the Stroop task, which is designed to test attention, and the n-back task, which is designed to test attention and also working memory. Many of these participants were also friends or colleagues of the research assistants. And as it so happened, some participants had mTBI and experienced concussion symptoms in the following year.
We had not anticipated this head trauma – it was unfortunate luck. But after the research assistants found out, they asked whether those participants would volunteer to be tested again while they had these concussion symptoms. They also volunteered for a 4-week follow up with the same tasks.
While the participants had concussion symptoms, they had much greater brain activation than before they experienced a concussion or during the 4-week follow up. These findings are in line with previous research on concussions, supporting the “microtearing hypothesis.”
According to the microtearing hypothesis, when we have a mTBI, we end up tearing or straining areas of our brain where the impact occurred. These microtears end up creating a sort of brain pathway detour, where pathways for cognitive functions like attention and memory are using alternate pathways in order to compensate for the detours created due to microtearing. Just like any city, the more detours there are then the more traffic occurs. The greater activation during concussion symptoms can be thought of as more traffic in your brain.
When a city detours a regular street, traffic begins to slow. The brain’s version of slow traffic would be an increase in neural resources – in this case, oxygen concentration. We increase the amount of oxygen also in order to compensate for the microtorn pathways. In other words, your brain may be doing more work than usual in order to make you act or behave as if you never were concussed.
Something interesting in these preliminary data is the fact that all participants performed with the same accuracy in all tests; in fact, reaction time was practically the same. These results were not expected, as our intuition suggested less accurate responses and slower reaction times during the concussion symptoms testing.
As I presented at the Cognitive Neuroscience Society conference in San Francisco, this particular finding has greater implications towards concussion testing protocols. The most common testing protocols are not too different from Stroop or n-back tasks; both report being able to test attention, working memory, non-verbal responses, and reaction time. These tests are reportedly reliable in assessing those who have experienced mTBI, and if someone pass either of these testing protocols then you may be able to return to play.
But if these testing protocols are essentially just behavioral measures – and our behavioral measures indicate there is no change in behavioral or reaction-time performance – then there is no way these tests are accurately assessing concussions that are not behaviorally taxing. Rather, these tests are giving the green light to many athletes who really should not be playing until recovered from their symptoms. Although these players may be able to physically return to play during the same game, repeated impacts to the brain can lead to not only greater lingering concussion symptoms, but also to permanent brain damage.
More research is necessary to better assess all types of concussions – not just severe ones – and brain imaging can help supplement designing better testes for concussions.
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