Neurofatigue & Brain Fog in Concussion Patients

Neurofatigue and brain fog are two of the most reported and long-lasting post-concussion symptoms. Your energy is low, even if you’ve managed to get a good night’s sleep; it’s hard to focus and remember things you used to automatically know; and some days the simplest everyday tasks seem downright impossible.

We can expect a person to feel tired in the hours and days immediately after a concussion. After all, the brain is experiencing an initial energy deficit due to dysfunction of the mitochondria. Mitochondria are like little power plants inside all the neurons and other cells throughout your body. Following a concussion injury, these become dysfunctional and have trouble keeping up with the demand for ATP production, which is your energy currency.

So, it’s inevitable that a person will feel fatigued immediately after a concussion injury.

But what about persistent fatigue that lasts for weeks or even months? What’s going on in this scenario? It turns out, a lot!

Concussions are a Systemic Injury

It’s not often talked about, but a concussion is a full-system injury. This means while your head and neck may have been the initial sites where the injury manifested, your entire body is affected, from your gut microbiome to your hormones and more! This quote is from a study published in 2007 on regulatory and autoregulatory physiological dysfunction as a primary characteristic of post-concussion syndrome: “We believe that the accumulating evidence suggests that concussion, while initially and primarily a brain injury, involves more than just a disturbance of cerebral cognitive function. It is a systemic injury that affects mutliple physiologic systems throughout the body.” [1]

Exposing Underlying Metabolic Weaknesses

The first thing we typically do with patients is run some bloodwork to see if they have any underlying nutritional deficiencies. The two biggest and most common deficiencies are iron and B12. You’d be surprised how many people have a low-grade iron deficiency. And when you don’t have enough iron, you can’t effectively transport oxygen into your cells, including the brain. So we tend to find patients with anemia (a condition in which you lack enough healthy red blood cells to carry adequate oxygen to your body’s tissues), which is a well-known cause of fatigue.

We also find a lot of patients are deficient in B12; a water-soluble vitamin necessary for proper metabolic function and mitochondrial production. Therefore, a deficiency in B12 can also cause fatigue.

You may be wondering; how we know these deficiencies are connected to the concussion? The answer is that we don’t necessarily directly link them to the concussion. But what we have learned, is that concussions tend to expose any underlying metabolic weaknesses present at the time of injury. You may have already had low iron or B12 levels prior to the injury, but not have known, and the injury becomes the catalyst for exposing them. Nutrients like B-vitamins and minerals are foundational building blocks to brain mitochondrial function and play a key role in brain fog.

To treat fatigue, we need to ensure your brain has an environment which is optimized for healing to occur. And the first step in this process is to look for and manage any nutritional deficiencies.

Activity Level

The old science indicated that people with a concussion should rest 24-hours a day. Yes, certainly within the acute stage (the first 24 – 48 hours after injury) concussion patients should participate in what is known as “sub-symptom threshold physical activity” – ie. take it very easy.

But is this the right approach when it comes to persistent concussion symptoms (PCS)?

No, it’s not. Research has clearly shown that aerobic exercise can improve brain function and increase brain chemicals responsible for repairing injured tissue. [2]

There seems to be a persistent misconception that physical activity should only begin after a patient’s symptoms have completely resolved. However, there is no scientific data that suggests complete rest is necessary nor effective beyond the initial period. In fact, a recent study of children and adolescents found those who engaged in physical activity during their recovery were less likely to go on to have persistent symptoms. [3]

Gut Health

If there’s one point to get across in this article, it’s that we must stop being hyper focused on concussions as solely a ‘brain’ injury. Initially, a concussion is a brain injury. But very soon after systemic affects also occur.

Here is a perfect example – roughly three hours after the initial brain injury, the permeability of your intestinal lining will be altered, affecting how your body responds to the foods you eat and your entire inflammatory processing for the duration of your recovery.

Leaky gut, another term for a change in intestinal permeability, allows the contents (protein and bacterial components) of the gut to leak into other areas of the body. The body then reacts by mounting a large immune response and resulting auto-immune reactions. This can mean odd rashes, joint pains, headaches, and sudden sensitivities to foods, and fatigue.

70% to 80% of your immune system is located within your gut. And, as we have just learned, a concussion can affect your Gut-Associated Lymphoid Tissue or GALT system. This is where all your brand-new immune cells are born and where they learn what is friend and what is foe. In other words, what is part of you and what is a foreign invader. If your gut health is affected because of a concussion, then your body may learn the wrong things to mount an attack against.

What we have recently discovered is that intestinal permeability is also related to other tissue and barrier permeability, including the permeability of the blood-brain barrier. It’s not just that the gut lining becomes more permeable, but your blood-brain barrier also becomes more permeable following a concussion. Now things are making their way into the brain that shouldn’t be, causing havoc for the central nervous system and this can have a wide range of physiological effects including depression and anxiety. [4]

In 70% of patients, this increased permeability will resolve within a couple of days. But for the other 30% experiencing persistent symptoms, they can and do experience ongoing headaches, brain fog and major fatigue. And so, the question becomes how do we treat this?

In this instance we start by addressing the leaky gut. We remove foods that are notorious for promoting increased permeability. This means cutting out gluten and refined sugars. It means taking care of the microbiome – the family of beneficial bacteria living in your gut. Eating probiotic-rich foods or taking a probiotic supplement as necessary.

Something many patients may be surprised to learn is that 90% of our serotonin – the feel-good neurotransmitter – comes from our gut. After a concussion, due to your gut health becoming compromised, you suddenly produce far less serotonin than before the initial incident. This means you may feel less happy, and for some even depressed. This can be a prolonged symptom of a concussion and another reason why people can experience significant ongoing fatigue.

In clinic the aim is to get people away from bad, processed foods and onto good, whole foods that promote good gut health.


By now you are starting to see that concussions affect a myriad of systems throughout the body. Concussions can also affect your hormones like thyroid, adrenal, and reproductive hormones. A 2017 study found that 16% of concussion patients developed new pituitary dysfunction over the 6-12 months after injury. [5] What we now know is that trauma, from a structural, blood flow and inflammatory perspective, and even an autoimmune perspective, can influence and change your pituitary gland. Your pituitary gland is your body’s master hormone gland. Located in your brain, the pituitary gland is responsible for producing ALL the precursor hormones for the glands listed above.

Hormones control your entire body. When your hormone levels are compromised, your health is similarly compromised. Most non-concussion literate doctors may not understand how a concussion affects your hormone levels. They may think you’re just tired and provide advice for you to continue “resting”. But really, your thyroid isn’t producing enough hormones and you now feel sluggish all the time. It is important to work with practitioners that specialize in concussion and understand how a concussion affects the entire body, from your brain to your gut, your hormones and beyond!


Just as concussions typically reveal underlying nutritional deficiencies, they can also expose underlying inflammatory disorders. For instance, following a concussion, patients may suddenly present with high rheumatological markers, which is just one example of systemic inflammation.

Concussion patients will also be dealing with local inflammation, present at the level of the nerve cells. Many patients also exhibit neurogenic inflammation, where the central nervous system becomes inflamed, but these markers may not show on bloodwork. They may have local myofascial inflammation, or joint dysfunction, which can be of an inflammatory nature. In fact, many of the headaches’ patients experience after a concussion can be related back to inflammation of the cervical spine.

How you deal with this inflammation and pain will impact some of the other systems and dysfunctions already mentioned. For instance, the patient who takes Advil all day to rid themselves of horrible headaches will end up disrupting their gut function, which can lead to leaky gut, and further inflammation. A vicious cycle!

Concussions are systemic, they affect the ENTIRE body. And therefore, we must constantly remind our patients with Post Concussion Symptoms, that the concussion itself is not really the issue anymore. The issues now typically live below the neck.


I want to end by restating a very critical fact, and that is that concussions are not simply a brain injury. While the initial injury may have been to the brain and neck, the goal is to heal and recover from the myriad of systemic changes that have occurred as a result. Concussions can lead to problems with mitochondrial health, gut health, hormonal health, mental and emotional health and more.

We encourage anyone who is suffering from prolonged fatigue and brain fog following a concussion to work with specialists who understand how a concussion can affect the ENTIRE body.

Complete Concussion Management is a network of trained multidisciplinary healthcare specialists that collaborate with physicians to co-manage concussion injuries, helping patients and athletes safely return to learn, work, and play.

Looking for concussion assessments, treatment or rehabilitation?

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Blog content adapted from ACD Podcast Episode 120 with Dr. Paul Hrkal ND – to listen to the full podcast click (here)