How Concussions and Repetitive Hits to the Head Can Affect the Human Brain
The side effects of concussions are increasingly receiving more attention. And for good reason. There is now much data connecting concussions with serious, long-term consequences that affect mental and physical health.1-3
In addition, scientists have determined that recurring hits to the head that don’t cause a concussion – like those acquired during contact sports – can have serious consequences over time. Their cumulative effects can damage the brain, leading to problems with memory, mood, pain, sleep, and movement, and even progressive brain disease.4
But don’t hang your cleats up and trade in your soccer ball for a ping-pong ball just yet. There are behaviors and lifestyle factors that can help protect your brain and keep it healthy while playing the sport you love.
What is a Concussion?
Concussion is a traumatic brain injury (TBI). Since the brain floats inside the skull, suspended in a protective cushion of cerebrospinal fluid, a strong impact to the body or a direct hit to the head or neck can shake the brain. If the impact is strong enough, it can cause the brain to bounce against the skull or twist. This can stretch and possibly even snap brain fibers and damage cells in the brain.1,5 When this happens, the delicate circuitry that connects one brain region to another can be disrupted. Maintaining these electrical and chemical connections is vital for normal brain function.
Although medical providers describe a concussion as a “mild” traumatic brain injury because it is usually not life-threatening, the short- and long-term effects of a concussion can be serious and even life-altering.
Symptoms and Effects of a Concussion
The symptoms of a concussion are often immediate – headache, dizziness, blurred vision, nausea, memory loss, or loss of consciousness. These symptoms can get worse, while other symptoms might not begin until hours or days after the injury. Contrary to popular belief, loss of consciousness is not common.5,6
Diagnosis often depends on the symptoms reported by the injured person – a headache, for example. Or from signs that other people notice, like a “dazed look,” confusion, or staggering. It might take a few days or even weeks to fully recover from a concussion – depending on the individual and the severity of the injury.1,5,6 It’s estimated that 10-30 percent of concussed individuals suffer symptoms that can last for many months or even years.7-9
Before returning to athletic competition, it is important to completely recover from a concussion – when symptoms disappear both while at rest and after exertion. Getting a second concussion before recovering from the first one can lead to long-lasting problems with thinking, attention, concentration, and other brain functions.1 In addition, repeated mild concussions that occur within a short period of time (e.g., hours, days, or weeks) can be fatal.1,6
Repetitive Hits to the Head Can Cause Long-term Damage
Recent research has found that repetitive hits to the head – even those that don’t result in concussion – can also lead to brain damage. Recurrent impacts that occur in contact sports like football, soccer, ice hockey, and boxing – or as a result of domestic violence or bomb blast waves – can damage the human brain.4,10,11
Eventually, these recurrent impacts can lead to a progressive brain disease called chronic traumatic encephalopathy (CTE). CTE is usually found in individuals who have had repeated head impacts, including concussions, during contact sports. CTE develops over a period of several years or even decades. Its symptoms include memory loss, personality changes, problems with anger and impulse control, depression, anxiety, and suicidal thoughts. As CTE progresses, some individuals experience dementia and motor symptoms like balance instability, tremors, and uncontrollable body movements.4,10,11
A February 2021 study reports that youth tackle football athletes ages 6-14 sustained 15 times more head impacts than flag football athletes during a practice or game and sustained 23 times more high-magnitude head impacts. The study recorded 186,239 head impacts over the course of a single football season.12
A 2017 study at Boston University examined 202 brains from deceased football players and found that 177 of them (87%) had signs of CTE from repeated hits to the head.13
At the present time, CTE can only be diagnosed after death. Intense research is currently being conducted to determine who is at risk of developing CTE, how to diagnose it during life, and what treatments can prevent it or stop its progression.14,15
Finding A Treatment for Concussion and Reducing Risks from Repeated Impacts to the Head
The current protocol for recovery after a concussion includes resting, slowly increasing physical activity, and avoiding screen time, alcohol, and other factors that make symptoms worse.
But for David Dodick, MD, Professor of Neurology and Director of the Concussion Program at Mayo Clinic in Scottsdale Arizona, that’s not good enough.
Dr. Dodick’s research is focused on finding nutrient therapies that can protect the brains of individuals who play contact sports, by minimizing the risks associated with recurring impacts to the head and accelerating recovery from a concussion.
Dr. Dodick’s clinical trials are examining how a cocktail of nutrients – beta-hydroxybutyrate (BHB), branched-chain amino acids, N-acetylcysteine, nicotinamide riboside, docosahexaenoic acid (DHA), and others – can provide protection to the brain of an individual who plays contact sports.
The Connection Between Long-term Inflammation and Concussions
Dr. Dodick explains that after a concussion, damage continues well after the initial injury – primarily sparked by ongoing (chronic) inflammation and an insufficient supply of energy required for brain cells to recover.
In experimental models, studies showed that repeated mild traumatic brain injuries caused chronic inflammation in the brain.16-18 Dr. Dodick believes that once inflammation becomes chronic, it damages brain cells and the delicate nerve fibers that connect one cell to thousands of others.
This breakdown in brain architecture can have lasting consequences and cause problems with thinking, processing information, and remembering. It can lead to physical symptoms like headaches and changes in mood and personality. Chronic inflammation also has a cascading affect that depletes the brain of crucial nutrients and reduces the ability of brain cells to produce enough energy for the brain to function normally.9,16-18
Dr. Dodick’s work explores how specific nutrients support healthy brain function, restore energy, and balance inflammatory molecules in the brain. He hopes to change the approach of managing concussion by treating the initial brain injury with a combination of these nutrients. He proposes this approach will help accelerate recovery from a concussion and minimize damage. The combination of nutrients might also help reduce or prevent the risks associated with recurring impacts to the head that are often incurred during contact sports.
Keep Your Brain Safe
It is important to understand that not every impact to the head will cause a concussion or have long-term effects. But no jolt to the head should be ignored. There are things every contact sport athlete can do to keep their head and brain safe – wear protective gear, properly secure a helmet, and utilize good sportsmanship to avoid head injuries.
For now, the best way to protect your brain is to avoid impacts and hitting your head. So be sure to buckle up, secure your gear, and practice proper techniques while playing your favorite sport to keep you and others safe.
- Centers for Disease Control and Prevention. Traumatic brain injury. Recovery from concussion. https://www.cdc.gov/traumaticbraininjury/outcomes.html. [Accessed April 1, 2021.]
- National Institute of Neurological Disorders and Stroke. Traumatic brain injury. https://www.ninds.nih.gov/disorders/patient-caregiver-education/hope-through-research/traumatic-brain-injury-hope-through. [Accessed March 3, 2021.]
- Martin T, De Beaumont L, Tremblay S, et al. Cumulative effects of concussions in athletes revealed by electrophysiological abnormalities on visual working memory. J Clin Exp Neuropsychol 2011;33(1):30-41.
- Gaetz M. The multi-factorial origins of Chronic Traumatic Encephalopathy (CTE) symptomology in post-career athletes: The athlete post-career adjustment (AP-CA) model. Med Hypotheses 2017;102:130-143.
- Mayo Clinic. Traumatic brain injury. https://www.mayoclinic.org/diseases-conditions/traumatic-brain-injury/symptoms-causes/syc-20378557. [Accessed March 3, 2021.]
- The University of Queensland, Australia. Concussion. https://qbi.uq.edu.au/brain/concussion/delayed-concussion-symptoms. [Accessed March 1, 2021.]
- Smith S. Post-concussion syndrome: an overview for clinicians. Psychiatr Ann 2017;47(2):77-82.
- Dwyer B, Katz D. Post-concussion syndrome. Handb Clin Neurol 2018;158:163-178.
- Dodick D. (expert opinion) Mayo Clinic. April 13, 2021.
- Aldag M, Armstrong R, Bandak F, et al. The biological basis of chronic traumatic encephalopathy following blast injury: a literature review. J Neurotrauma 2017;34:S26-S43.
- Graham R, Rivara F, Ford M, et al. Sports-Related Concussions in Youth: Improving the Science, Changing the Culture. Institute of Medicine; National Research Council. Washington (DC): National Academies Press (US); 2014 Feb 4.
- Waltzman D, Sarmiento K, Devine O, et al. Head impact exposures among youth tackle and flag American football athletes. Sports Health 2021 Feb 23:1941738121992324.
- Mez J, Daneshvar D, Kiernan P, et al. Clinicopathological evaluation of chronic traumatic encephalopathy in players of American football. JAMA 2017;318(4):360-370.
- Turner R, Lucke-Wold B, Robson M, et al. Repetitive traumatic brain injury and development of chronic traumatic encephalopathy: a potential role for biomarkers in diagnosis, prognosis, and treatment? Front Neurol 2012;3:186.
- Katz D, Bernick C, Dodick D, et al. National Institute of Neurological Disorders and Stroke Consensus Diagnostic Criteria for Traumatic Encephalopathy Syndrome. Neurology 2021 Mar 15:10.1212/WNL.0000000000011850.
- Lyman M, Lloyd D, Ji X, et al. Neuroinflammation: the role and consequences. Neurosci Res 2014;79:1-12.
- American Academy of Neurology. The link between concussion and inflammation. https://n.neurology.org/content/neurology/93/5/e526.full.pdf. [Accessed April 1, 2021.]
- Patterson Z, Holahan M. Understanding the neuroinflammatory response following concussion to develop treatment strategies. Front Cell Neurosci 2012;6:58.