Announcement of a potential blood test for CTE opens the door for many new questions

This week, researchers at Boston University’s Chronic Traumatic Encephalopahty (CTE) Center announced that they may have identified a biologic marker that could be measured in blood or cerebrospinal fluid (CSF) of living athletes to diagnose CTE. Currently, researchers have only been able to definitively diagnose the chronic brain injury in athletes post-mortem by examining cadaver brain tissue. The BU CTE Center published an article in the science journal PLOS ONE stating that researchers found an elevated level of the protein CCL11 in brain tissue and CSF of deceased athletes with diagnosed CTE compared with deceased patients with diagnosed Alzheimer’s disease and non-athlete “control” cadavers.

This discovery is an exciting one because it may be used to give us a much better understanding of the natural history of a devastating disease that, up until this point, we don’t know enough about.

But man, has this announcement opened up a can of worms for future and current NFL & NHL athletes.

There’s a new test for CTE in living athletes. Does that mean all pro athletes will be mandated to take it? If it’s positive should they quit? Will the NFL/NHL/fill-in-the-league force them to? Will athletes be tested at the combine? Will their insurance companies find out? Will their significant others find out? Does a positive test mean they’ll end up either demented or a violent murderer?

Ok, maybe those were just my questions. I’m sorry, I’ve been binge-watching the HBO series Ballers and The Rock has some issues he’s working through…

This is a great article with reaction from some of the Toronto Maple Leaf players about news of a possible new CTE test. When asked about whether or not their athletes would be willing to be tested, coaches and agent responses ranged from “none of my guys would take that test” to “maybe 75% would.”

When new tests are discovered in medicine, the most important question is this – What does a positive result mean? If we develop tests for conditions or tests for risk factors for conditions and don’t know what to tell patients to do with those results then we’re not doing our job and the results of the test are meaningless and anxiety-provoking.

Let’s imagine that the CCL11 protein is a great marker for CTE and scientists are able to reliably measure levels in either CSF or blood samples. The next step will be figuring out what levels are considered “normal” and what levels are considered “elevated.” That requires studying a lot of living people to figure out. Let’s say they establish a normal range and can tell patients if their level of CCL11 is elevated. The next question is what does that mean? The only way to know the answer to that question is to prospectively (meaning from a young age for years) follow athletes and non-athletes for head trauma, neurologic symptoms, and regular measurements of their CCL11 protein levels to see what happens to people with elevated CCL11 tests over time. If advanced imaging by then cannot tell us if those patients developed CTE by looking scans then post-mortem examinations of their brains will be needed to say if they ever developed true CTE. Knowing all of the above information is the only way for us to use the test to actually try to help athletes potentially avoid worse chronic brain insult.

Imagine you’re a 24 year-old slot receiver. You’ve had more hits in high school and college that you can (gasp!) remember. You have a bright career ahead of you. You’re not sure what to do but your Mom “suggests” you get tested. Your CCL11 marker is elevated. What do you do? If it was done today,  you would immediately become terrified that your career is over and you’ll be a vegetable by the age of 40. Because that’s the news you hear on TV. The hope is that if and when definitive testing for CTE is available, doctors will be able to council athletes on what a positive test means. For example, right now we don’t yet know if all of the “damage” is done by a certain age and future hits don’t affect the course of the disease. That’s an important detail and one of MANY. Furthermore, the link between concussions and CTE is not definitively established so does number of concussions definitely matter? Once test results are delivered we also need to give athletes options of what they can do to stop further damage and advice on whether or not that will even result in a difference in their outcome down the road. We don’t know what that advice should be yet.

What I want sports fans and athletes to know is that there are a LOT of unknowns when it comes to CTE. The media blitz earlier this week about a possible new blood test on the horizon was likely anxiety-provoking for many athletes for good reason. Researchers have a huge job ahead of them learning more about the natural history and causes of a disease that we still don’t understand very well.


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