Why do some people recover from concussions while many others don’t?
Prevailing hypotheses and ideas about the causes of post-concussion syndrome
What causes post-concussion syndrome?
Many thousands of people suffer a concussion or mild traumatic brain injury (mTBI) every year, and a significant percentage of them (currently millions of people in aggregate) continue to struggle for months, years, or perhaps indefinitely. The collection of symptoms they experience is often called post-concussion syndrome (PCS).
We know that a concussion is not a diagnosis, it is a mechanism of injury. Post-concussion syndrome might sound more like a diagnosis, but again, it’s really a label slapped on a set of common symptoms. It doesn’t get us much closer to answering key questions.
Perhaps the biggest question of all is: Why do some people recover from concussions while others don’t?
While the long answer to this question is complex, to say the answer is a complete mystery is to lie by omission. By way of comparison, we may not know all the details about how the universe began, but we have many solid ideas about it based on observable evidence—stars and galaxies are moving away from a shared origination point, for example.
Thus, “Here’s what we know…” is the proper place to start.
What I’d like to do here is lay out, in very straightforward terms, the prevailing hypotheses and ideas about what causes lingering “post-concussion syndrome” in order to give the many millions of people who suffer in the aftermath of a concussion some basis for understanding and recovery.
I’m structuring this newsletter a little differently. It’s going to be like one of those movies that starts at the end and then goes back to the beginning. We’re going to start with the reasons why symptoms linger, then go back to the primary causes of injury to connect the dots.
Lingering symptoms seem to be caused by five things
One of the standard answers for why some people don’t recover from concussions has to do with how many concussions one has suffered, and what one’s biological age was when those events occurred. This is related to the availability of stem cells in the brain (at a young age, you have a storehouse of these), which I’ll touch on later.
While I could count this as one of the factors (it is a factor), I’m not going to dwell on it here because there isn’t anything one can do about it. None of us chooses when to get injured.
Along with the primary injury (the specific damage caused by the initial concussive event) the unresolvable nature of lingering symptoms seems to come down to five things.
These five things can operate alone or in concert. Unlike our age, we can have some influence over these.
One: Inflammation in the brain (initial inflammation as well as chronic)
The first reason symptoms might linger is inflammation.
Inflammation around the injury site in the brain can linger and cause a cascade of problems that further damage the brain, effectively becoming a negative feedback loop.
Lingering inflammation probably plays a role in the struggle to perform cardiovascular exercise after a concussion without provoking symptoms.
It is now thought that damage caused by lingering inflammation plays a key role in disrupting the brain’s ability to manage (throttle or suppress) incoming sensory information. Thus, the struggle with sensory overload.
In recent animal trials, specific inflammatory responses were blocked in the brain, and this seemed to prevent secondary injury and post-concussion syndrome.
Many emerging treatments center on the early stage (within days of the event) limiting of inflammation in the brain through mechanisms such as cooling the head. Certain foods and supplements can also help limit inflammation.
Note: If you’re reading this and thinking you can just take a bunch of Advil or aspirin, don’t. Standard medical advice is that Tylenol is the only over-the-counter anti-inflammatory drug that one should take in the aftermath of a concussion. Then again, how long can one simply take Tylenol?
In any long-term recovery scenario, addressing sources of inflammation becomes an area of focus. There is now a fairly vast literature about this, and much of the focus is on diet.
There are several reasons why the modern diet can lead to a leaky gut and leaky blood-brain barrier. Consumption of common ingredients (including certain oils and emulsifiers) in highly processed foods can damage the mucosal lining of one’s digestive system, and perhaps one’s blood-brain barrier. If this condition was present at the time of one’s concussive injury, recovery will be that much more difficult.
Until the day when it’s common practice to block the damaging levels of inflammation that occur after an mTBI, people will need to focus on the levers they can control, which include: diet, supplementation (including anti-inflammatory supplements such as curcumin), specific breathing techniques, exercise, and light exposure (including sunlight, specific forms of laser light, etc).
Two: Neural network discordance
The second reason symptoms might linger is neural network discordance.
The neural networks of the brain, principally the default mode network, are struggling to properly re-establish themselves or fire together, which causes a cascade of dysfunction and "noise” that becomes a negative feedback loop.
This could be caused or exacerbated by lingering inflammation. It might also play a separate but related role in neuro-vascular decoupling. The link between the firing of neural networks and the vascular action needed to supply blood to the relevant areas is somehow dysfunctional and must be repaired.
A neural network is like a chord played on a piano. The same keys (neurons, areas of the brain) can be played in a great variety of chords for different purposes, allowing the instrument (the brain, a piano) to do an infinite variety of things with a small set of “keys.” But if the brain can’t hit a “chord” (for example, a neural network associated with performing a certain task) it is discordant.
Behavioral practices such as meditation (with or without neurofeedback) and treatments such as the Vielight are aimed at re-establishing the default mode network, which seems to be a foundational neural network (functioning perhaps like middle C on a piano).
Other treatments such as transcranial magnetic stimulation, neurofeedback, and binaural apps, can support the brain in its efforts to activate neural networks. TMS has been proven effective for this purpose. It’s a little more conjectural with the other therapies, but I personally have found them helpful for this purpose.
Three: Neurotransmitter imbalance
The third reason symptoms might linger is ongoing neurotransmitter imbalance.
Perhaps as a consequence of the first two issues, or perhaps due to the nature of one’s primary injury site, or perhaps due to the emotional strain of dealing with all this, the proper balance of neurotransmitters in the brain (including dopamine and serotonin) is disrupted and the brain struggles to re-establish balance. Again, this forms its own negative feedback loop.
Anti-depressants or SSRIs have been a go-to treatment for this issue. They can be really helpful. I took them for a few years. I eventually transitioned off of them. A side effect of SSRIs for me was dizziness, which made it impossible for me to address my vestibular issues.
There are supplements one can take to influence neurotransmitter levels. These include 5-HTP and L-Tyrosine. I’ve tried both of these and found that the trough (the experience of the low point) didn’t justify the peak (the experience of the high point). Needless to say, you shouldn’t try these if you’re already taking an SSRI, and I strongly advise you to consult with a relevant and trusted medical professional before adding or removing anything from your regimen.
I want to mention that TMS therapy is FDA approved for drug-resistant depression. In this sense, TMS seems to be an effective treatment when addressing the neural network issues mentioned above as well as some of the neurotransmitter issues. TMS is available in a clinical setting and with devices such as the NeoRhythm.
Four: Vestibular dysfunction including oculomotor issues
The fourth reason symptoms might linger is vestibular dysfunction, including related oculomotor issues.
One or more components of the vestibular system (inner ear, eyes, neck, sensorimotor neurons, or the brain’s central processor that takes in or suppresses information coming from this balance information) are damaged and the brain must re-learn how to take in and process incoming sensory information about where the body is in space.
If one is suffering from some level of PTSD, you can imagine how not knowing where one is in space can form a negative feedback loop here as well, producing levels of anxiety that themselves make one dizzy.
Vestibular dysfunction is best addressed by a vestibular therapist, a PT who specializes in vestibular training. The way a human being maintains balance is quite complicated and a specialist can evaluate exactly where your issues may be (a sensor issue or a processor issue, for example). Vestibular.org has more information. Vestibular retraining is a long process that requires daily work. It could involve some level of related vision therapy, including a course of syntonic light therapy. It will likely involve neck treatments, including manual joint manipulation or acupuncture.
Five: Dysfunction in the upper cervical area of the neck
A head injury often involves some level of whiplash or neck damage. Soft tissues in the neck may be damaged. Structures in the neck may be damaged or dysfunctional.
If these issues are overlooked and unaddressed, one may experience a range of symptoms that are fairly debilitating.
See previous newsletters about neck treatments, including PT, Atlas Orthogonal Chiropractic, and acupuncture.
If any of these five areas form negative feedback loops, and if those loops interact with each other, one can get a perfect storm that exacerbates and perpetuates each problem. A kind of red spot of Jupiter scenario.
Now that we’ve covered the ending, let’s go back to the beginning and look at the current thinking about the causes of primary injury. This will allow us to connect the dots between the nature of the initial injury and how those can land us in a state where symptoms are very slow to resolve.
Primary causes of injury
I want to emphasize that I’m talking about mTBI here, which is what I suffered personally. I’m not addressing more severe traumatic brain injuries. There may be some overlap, but if there is, it’s definitely not for me to say—I am not a medical professional, see disclaimer below.
Here are the prevailing ideas about how a brain gets injured in a concussive event, with an emphasis on how this information is relevant to the recovery process.
One: Damage is done to the brain’s vascular system and perhaps the blood-brain barrier
The brain is often thought of as a collection of neurons. It’s really a nexus of the nervous and vascular systems. Much of the brain is vascular.
Without a huge volume of blood flowing into and out of the brain every minute of your life, the neurons wouldn’t get the nutrients and other things they need to function.
If this vascular tissue is damaged, the brain and body will begin self-repairing it (as with any other injury to the body). This repair will involve inflammation at the sites of injury in the brain.
Inflammation plays a positive role in healing injuries, but as most of us know from dealing with injuries to the body, excessive inflammation or chronic inflammation can become a real problem in itself, one that creates further downstream problems (this is a feature of many autoimmune diseases). If this happens in the brain, you can imagine how it would lead to an inability to recover as best one can.
This issue of inflammation in the brain can be compounded by a leaky blood-brain barrier, where all that blood going into and out of the brain every minute is both helping and hurting the brain because the blood-brain barrier is compromised.
It may be that damage to the brain’s vascular system directly causes a leaky blood-brain barrier around the site of injury. If true, one would then have to put an extremely fine point of emphasis on what one is eating. For example, anything that causes even a mild allergic reaction could perpetuate a state of chronic inflammation in the brain.
If one has a leaky gut or leaky blood-brain barrier prior to a concussion, that creates the condition for a difficult recovery. One may need to make radical and probably permanent changes to one’s diet.
How can one determine if there is inflammation in the brain? Are there biomarkers for that?
Yes, there are biomarkers, and routine tests for these biomarkers (via saliva) are about to become a thing for professional athletes. This is cutting edge stuff. In the future, such tests will likely be available at pharmacies. As of this writing, such testing is largely unavailable. Certain blood tests can reveal biomarkers for general systemic inflammation. You could ask your doctor about doing such a test. However, even if the test is positive, where does that leave you?
How can one increase or enhance one’s vascular health in order to better support the brain’s vascular system, the healing process, overall health, and brain health?
The levers we can control for overall vascular health include specific breathing exercises (read the book Breath by James Nestor), cold exposure (Wim Hof Method for example), exercise, diet, and some of the treatments I’ve outlined in previous newsletters.
You might be wondering: What does a healthy blood-brain barrier let through? Among other things, O2 and CO2. In the aftermath of certain types of concussive injuries, does a dysfunctional blood-brain barrier struggle to let in proper amounts of O2 and CO2? Maybe. I’m not aware of any studies that have looked at that specifically. But to me, this puts breath work on an equal footing with diet and exercise as a behavioral pillar of recovery. As a starting place, read Breath by James Nestor.
Two: Damage is done to neurons, glia, and other nervous system tissues or structures in the brain
The thinking here is that, as an energy wave moves through the brain (from a blow to any part of the body, a blast injury, a ball, a collision, etc) sheering forces are created as the wave moves through tissues and structures in the brain with different densities. These forces can damage or destroy neurons and glia (as well as vascular tissue mentioned above).
One hypothesis is that synapses (the gaps across which neurons fire, sort of like spark plugs) can get stretched too far apart and therefore can’t fire across the gap anymore.
The good news is that the current science tells us that the brain can repair this damage. There have even been some animal experiments where stem cells were injected, and the brain was able to use them for such repairs.
Sure, it’s nice to have some theoretical basis for the possible nature of your primary neuronal injury, but in the absence of A) Commonly available scanning tech that can pinpoint your injury sites at the neuronal level and B) Noninvasive tech that can treat or repair a specific neuronal injury site, what good does this information do you?
At the present time, the levers you can control in this area include: supplementation for brain health (including amino acids), behavior changes for brain health, diet and exercise for brain health, specific breathing techniques for brain health, and the many treatment options I’ve written about in this newsletter.
Three: Damage is done to the lymphatic drainage system in the brain or it becomes inflamed
The lymphatic drainage system in the brain was only recently discovered. However, it already seems clear that its dysfunction (whether through damage or inflammation) plays a key role in certain neurodegenerative conditions such as Alzheimer’s and CTE.
It makes sense: If the brain can’t clear out the gunk every day, bad things build up. It’s like NYC with a garbage strike on.
Since this drainage system is most active during specific phases of sleep, and since so many people struggle to get quality sleep after a concussive injury, this alone can form a negative feedback loop where the brain can’t clear what it needs to clear and therefore can’t really heal.
This should put a double underline on the importance of regaining and restoring quality sleep. For me, that hinges on aligning myself with the circadian rhythm, and other practices that I’ve outlined in this newsletter.
Drainage also happens during the day. Taking a 30-minute walk every day will help stimulate drainage. It’s one reason why walking is a foundational practice.
Four: Damage is done to key parts of the neck
This can be a primary source of the lingering symptoms so many people suffer from, and it often gets completely overlooked.
The neck is like a brain-body interface. It plays an essential and tightly integrated role in our balance system and, needless to say, everything your brain needs (from blood to cerebrospinal fluid) has to flow through your neck. Should the Atlas bone get damaged or knocked significantly off-kilter, the structures that deliver these fluids to your brain will be constricted.
Okay, so we started at the end, then went back to the beginning, and should now have a sense for the big picture.
The reasons why so many people suffer today isn’t entirely a mystery. Yes, a lot remains unknown—the human brain is the most complex thing we know of in the universe—but we also know a great deal already.
It seems to keep coming back to the same set of issues: inflammation (initial inflammation as well as chronic), neural network discordance, neurotransmitter imbalance, vestibular dysfunction, and upper cervical dysfunction.
When you survey new and developing treatments, they are focused on one or more of these areas.
In the future, treatments for concussive injuries will include a range of things that prevent and treat post-concussion syndrome. These will likely include:
Injections of specific inflammatory response inhibitors in the immediate aftermath of a TBI. (Already proven effective in animal trials.)
Devices that keep the brain and body cool to limit inflammation. Or cold exposure techniques, such as submerging one’s body and head in cold water, as in the Wim Hof Method. (These methods have already been validated to a certain degree, although more research and validation is ongoing)
Saliva tests for monitoring the progression of brain inflammation. (This is now happening in the Premier League.)
Scanning tech that can reveal the exact location and scale of damage, whether it is neuronal, vascular, or both. (Multiple entities are racing toward this from various angles.)
The injection of stem cells that a brain can use to repair itself. This is the one treatment that addresses the age-at-injury factor. (Already proven to work in animals.)
The use of non-invasive technologies, such as TMS and pulsed light, can further help the brain heal. (Already available in a somewhat crude form. I expect more devices and more precision in the future.)
Patient training in specific practices such as rehabilitative exercises, diet, breathing, and more. (Apps and sensor technologies will continue to improve and help deliver this kind of thing to people who need it.)
Added to these will be the future versions of treatments I’ve written about in this newsletter. As always, I hope this information helps you and your loved ones.
Brainwave is an informational resource for people whose symptoms haven’t resolved after a concussion or mTBI. I endeavor to present this information in a clear and concise way, spelling out what’s backed by science and what remains unknown. Nothing here is meant as a substitute for professional medical advice, diagnosis, or treatment. I am not a physician or a healthcare practitioner of any kind; I’ve simply had a lot of sports-related concussions and had to learn this stuff the hard way. If you found this information helpful or know someone who might benefit from it, please share and subscribe to Brainwave.