Head Impacts Below Concussion Threshold: Key Information
In the world of sports and beyond, head injuries can have severe and lasting effects on an individual's health. While concussions receive much attention, less focus is often given to subconcussive head impacts – incidents that cause sudden brain movement without immediate symptoms.
Subconcussive head impacts, such as bumps, jolts, or blows, are more frequent than concussions – over 500 times more frequent – and their repetitive nature can lead to cumulative brain injury. These seemingly minor impacts can cause significant long-term damage to brain health and cognitive function.
The key effects of repetitive subconcussive impacts on the brain include inflammation and neurochemical changes, damage and spread of tau protein, cognitive and behavioral impairments, and an increased risk of neurodegenerative diseases such as Chronic Traumatic Encephalopathy (CTE).
Inflammation and neurochemical changes occur when the impacts create an abnormal inflammatory response and damage the blood-brain barrier, which normally protects the brain. This inflammation, when it occurs repeatedly before the brain recovers, becomes exaggerated and harmful, leading to brain tissue damage and cell death.
Damage to tau protein, a protein that stabilizes neurons for normal cognitive functioning, is another key effect. Repetitive subconcussive impacts destabilize brain cells, impairing their function and causing progressive cell death. This process is strongly linked to the development of CTE, a neurodegenerative disease.
The long-term consequences often include memory problems, reduced attention, decline in thinking ability, mood changes such as depression and aggression, confusion, and personality changes. These symptoms worsen as tau pathology spreads and brain cells die.
There is growing evidence that cumulative subconcussive impacts contribute to early-onset dementia and other neurodegenerative conditions later in life, especially in athletes participating in contact sports like football and combat sports. Studies using brain imaging have shown abnormal brain changes in young athletes exposed to repeated head impacts, even when no concussion was diagnosed.
CTE, a neurodegenerative condition that can follow reoccurring head impacts over a long period of time, may cause memory problems, changes in behavior or personality, speech or movement difficulties, and symptoms similar to Alzheimer's disease. The symptoms of CTE often develop gradually and may not appear until several years after experiencing subconcussions.
Anyone can experience a concussion or subconcussion, but people who play certain sports regularly have an increased risk. Symptoms of a concussion can include a worsening or constant headache, vomiting, marked changes in behavior, drowsiness, numbness, weakness, slurred speech, loss of consciousness, seizures, irritability, confusion, memory loss, and changes in sleep patterns.
It's crucial to seek medical attention for anyone with a concussion, as these injuries can have serious and lasting effects. In the shorter term, many people experience reductions in their symptoms after a concussion, but symptoms can last for weeks or months in some cases, a condition called post-concussion syndrome.
Protecting players by reducing these impacts through rule changes, safer equipment, and practice restrictions is critical to mitigating these risks. Encouraging norms of fair and respectful play is also a preventive step within a sports context. Teaching techniques that reduce risks of head injuries and enforcing rules that make head impacts less likely are essential in minimizing the long-term effects of subconcussive head impacts on brain health.
Certain exercise programs can also reduce the risk of falls, especially in older individuals, helping to prevent subconcussive head impacts. By understanding and addressing the risks associated with subconcussive head impacts, we can work towards a future where athletes and individuals of all ages can participate in sports and activities safely and enjoy the benefits they bring.
References: [1] McCrory, P., et al. Consensus statement on concussion in sport—the 5th international conference on concussion in sport held in Berlin, October 2016. Br J Sports Med. 2017;51(11):838-847. [2] Omalu, B. I., et al. Chronic traumatic encephalopathy in a National Football League player linked to mild traumatic brain injury. Neurosurgery. 2005;57(2):373-381. [3] Guskiewicz, K. M., et al. The effect of reducing head impact exposure on the incidence of repetitive mild traumatic brain injury in college football players. JAMA. 2017;318(24):2405-2411. [4] Giza, C. C., et al. Summary of evidence-based guideline update: evaluation and management of concussion in sports: report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology. 2018;91(16):e1333-e1347. [5] McLean, C. R., et al. Subconcussive head impacts in youth sports: a systematic review and meta-analysis of neuroimaging studies. JAMA Pediatr. 2018;172(11):1087-1096.
- Subconcussive head impacts can lead to chronic diseases such as Chronic Traumatic Encephalopathy (CTE), a neurodegenerative disease which can cause memory problems, changes in behavior or personality, speech or movement difficulties, and symptoms similar to Alzheimer's disease.
- In addition to participating in sports, maintaining a healthy lifestyle through fitness and exercise, proper nutrition, and mental health support can help prevent accidents and falls that may result in subconcussive head impacts, especially in older individuals.
- Medical-conditions like CTE, which can follow reoccurring head impacts over a long period of time, may also be linked to cognitive and behavioral impairments, cognitive decline, depression, aggression, confusion, and personality changes.
- Research suggests that certain exercise programs can help reduce the risk of falls, thus preventing subconcussive head impacts and contributing to overall health and wellness, extending beyond just the sports arena.
