Chronic Traumatic Encephalopathy (CTE)

What Is Chronic Traumatic Encephalopathy (CTE)?

Chronic traumatic encephalopathy (CTE) is a brain condition that results from repeated concussions and mild brain injuries, such as impacts to the head caused by things like heading a soccer ball or hitting your head on a mat during martial arts training. These repeated impacts to the head can lead to minor injuries to neurons in the brain. Over time, the injuries accumulate, and neurons begin to die.

CTE causes issues with brain functions and tends to get worse over time. It occurs mainly in athletes who suffer repeated hits to the head, like boxers and football players. Researchers are working on understanding why repeated injury can cause CTE in some people but not in others.

Symptoms of CTE

Symptoms of CTE appear slowly and are sometimes difficult to identify in the early stages. Because CTE is a progressive disease, over time, people with CTE may have symptoms similar to dementia:

• Memory loss
• Confusion
• Difficulty making decisions
• Sleep disturbances

People with CTE may also have other neurological symptoms like anxiety or depression, difficulty sleeping, dizziness, or balance issues.

Symptoms of CTE don’t always start when the person is experiencing repeated head impacts. In some cases, symptoms can begin decades after the last head impact. As with other degenerative conditions, symptoms do not disappear or get better, but with support, a person with CTE can adapt to some of these changes.

What Causes CTE?

CTE is caused by repeated hits to the head. Some examples of activities that are associated with CTE are:

• Soccer
• Football
• Martial arts
• Military activity, including exposure to blasts
• Rugby
• Ice hockey

Repeated injury, although mild, may cause the cells in the brain to accumulate a protein called tau. Tau is a protein that everyone has in their brains. It helps move nutrients in the brain and spinal cord and molecules that help with communication between neurons. However, when neurons are damaged, tau builds up in and around them, causing them to die.

Tau spreads from one neuron to another, a process that is unique to CTE. This spread occurs very slowly. Over time, the accumulation of tau in the brain is associated with reduced brain size. This brain atrophy is thought to be the main cause of symptoms of CTE.

Who Is Most At Risk for CTE?

Anyone with a history of repeated blows to the head can get chronic traumatic encephalopathy. Athletes who engage in contact sports like boxing and football and military veterans who are exposed to repeated blasts from explosives are at a heightened risk.

The risk also increases with time; each year in which a person engages in these activities is associated with a 15% increased risk of being diagnosed with CTE. Another way to think about this is with every 1,000 blows to the head, the risk of CTE increases by 21%.

Additionally, emerging evidence suggests that a person’s genes may contribute to whether or not they develop CTE. Mutations in one gene called TMEM106B may be more common in people who are diagnosed with CTE. TMEM106B provides the genetic code for a protein that helps move lysosomes to where they are needed in a cell. Lysosomes are responsible for removing proteins that are worn out or damaged and need to be replaced.

The role of genetics is being actively researched. This will help healthcare providers better understand whether a person may be more susceptible to developing CTE than others.

How Common Is CTE?

CTE is a rare disease affecting less than 1% of the population. However, the rate among athletes playing high-impact sports could be much higher.

Several studies have shown that even amateur players are at high risk. A study conducted by Boston University in 2023 showed that nearly 40% of the student-athlete’s brains showed early signs of the disease.

How Is CTE Diagnosed?

Chronic traumatic encephalopathy is suspected when someone has a history of repeated head injuries and is exhibiting symptoms of CTE. However, a definitive diagnosis requires that the brain be observed during an autopsy. A pathologist can examine the brain for tau and diagnose CTE based on the pattern of tau accumulation.

Although tau protein accumulation is also observed in Alzheimer’s disease, the distribution in the brain is different in CTE. Unlike Alzheimer’s disease, tau accumulation is uneven, spreading from the surface of the brain inward, making it difficult to determine while a person is living. However, more powerful imaging techniques are being developed to identify this earlier.

Therefore, imaging techniques like magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) may help healthcare providers determine whether the person’s symptoms may be attributable to CTE.

While someone is alive, a healthcare provider may collect evidence for CTE that includes:

• The degree of exposure to repeated head injury
• Imaging of the brain
• The presence of symptoms not accounted for by other psychiatric, neurologic, or medical conditions
• Cognitive issues
• Mood disorders like anxiety or depression
• Behavioral changes, such as problems with making sound decisions or impulsivity

Methods for detecting markers in the blood are being developed for early diagnosis. Researchers are testing the idea that repeated blows to the head may make tiny holes in the barrier between the brain and blood. Tau may leak into the blood; sensitive tests could be developed to detect this before symptoms occur.

Can You Treat CTE?

Because CTE cannot currently be diagnosed while someone is alive, there are no specific treatments for CTE. However, certain mental health medications and interventions may help with the symptoms of CTE, much like those prescribed for dementia. These are called supportive therapies because, although they are not aimed at curing the disease, they may help a person live as independently as possible with CTE. Supportive therapies for CTE include:

Physical Therapy

Physical therapy helps people with CTE regain strength and endurance. Specific exercises may be recommended to reduce headaches and improve balance. A physical therapist may also prescribe rest to promote healing.

Meditation and Yoga

Meditation and yoga may help reduce stress and inflammation. These mindfulness practices can also reduce anxiety by encouraging awareness of triggering thoughts and breaking the cycle of worry.

Aerobic Exercise

Aerobic exercise has many benefits, like improving brain plasticity, or the ability of the brain to adapt. It can also increase blood flow in the brain, which can enhance the survival of neurons. Aerobic exercise can include bike riding and walking.

Occupational Therapy

Occupational therapy focuses on training people in specific skills that help in everyday life. Examples include shopping, returning to work or school, social skill development, home management, and self-care.

Vestibular Rehabilitative Therapy

Vestibular rehabilitative therapyaims to treat balance issues and dizziness. It includes strength training, stretching, and exercises that improve eye movements and coordination.

Some medicines used for Alzheimer’s may also benefit a person with CTE. Donepezil, for example, may help with memory loss, while memantine could slow the death of neurons in the brain. Other medicines can address the symptoms of CTE, like antidepressants, antianxiety medications, and medicines that help with shaky muscles that produce tremors.

The good news is that tau accumulation and symptom development are slow-moving, which means there are opportunities to intervene before symptoms progress.

Can I Reduce My Risk of Developing CTE?

Because CTE is caused by repeated head injuries, prevention of CTE is focused on protecting the head. Methods for reducing the risk of developing CTE include:

• Using protective equipment when playing high-risk sports
• Seeking prompt medical attention when a head injury is suspected
• Avoiding high-risk behaviors that could result in mild head injuries
• Consider using new technologies that help prevent concussions, like deformable helmets made by VICIS

When Should I See My Healthcare Provider?

People with a history of repeated head injuries should be aware of the symptoms of CTE. Important symptoms to pay attention to are memory issues, difficulty focusing or making decisions, suicidal thoughts, aggression or impulsive behavior, and mood disturbances.

When these symptoms arise, even if it’s years after you stop engaging in the activity that caused the injuries, you should see a healthcare provider as soon as possible.

Even without a history of repeated injury, you should seek medical attention right away if you have sustained a head injury.

The Road Ahead

Chronic traumatic encephalopathy symptoms can develop many years after head injuries occur. Being assessed by a healthcare provider as early as possible can help them identify therapies that could help you remain as independent as possible. Although there is no cure for CTE, there are many supportive therapies that may slow the progression of symptoms and allow you to live a full, healthy life.