Chronic Traumatic Encephalopathy (CTE)

Chronic traumatic encephalopathy (CTE) is a degenerative brain disorder that happens due to repeated head impacts. This condition usually affects athletes who play contact sports, but can affect military personnel and people who participate in other sports and activities. Preventing head injuries is the best way to address this permanent condition.


Damage from chronic traumatic encephalopathy disrupts processes throughout your brain.
The symptoms of chronic traumatic encephalopathy can disrupt processes throughout your brain. As this condition worsens, it can cause disruptive or aggressive behavior.

What is chronic traumatic encephalopathy (CTE)?

Chronic traumatic encephalopathy (CTE) is a brain condition that can develop due to repeated head impacts and concussions. This condition affects how areas of your brain function, communicate and work with each other. Depending on the extent of the damage and the affected brain areas, this condition can have severe effects.

CTE is best known for affecting professional athletes in contact sports, especially boxing, American football and ice hockey. However, this condition can develop in people with repeated head impacts regardless of their sport (or if they don’t play sports at all). Healthcare providers also identify it in military veterans who experienced multiple explosion- or blast-related incidents.

The name of CTE breaks down like so:

  • Chronic: This means CTE is a long-term condition.
  • Traumatic: This term means CTE is trauma- or injury-related.
  • Encephalopathy: This combines two words from ancient Greek. The literal translation means “brain disease.”


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Who does chronic traumatic encephalopathy affect?

Chronic traumatic encephalopathy can affect anyone with a history of repeated blows to the head. However, CTE also doesn’t appear immediately. For most people with this condition, it can take years or decades before symptoms are severe enough to draw attention. People who develop CTE typically have a history of many head impacts over several years, especially people who play sports professionally. The vast majority of people who play high school sports don’t develop CTE. In fact, the average age of people with confirmed CTE is around 42 to 43 years old.

People who have the greatest risks include:

  • People who participate in combat-centered sports and competitions. This especially applies to boxing, mixed martial arts (MMA) and other traditional forms of martial arts (tae kwon do, aikido, judo, etc.)
  • People who play contact sports, especially football, ice hockey and rugby.
  • People who participate in road/concrete-based activities like cycling, rollerblading, skateboarding, etc.
  • Military personnel exposed to explosions and other concussive events.

How common is chronic traumatic encephalopathy?

Experts aren’t sure just how common CTE is. That’s partly because there’s no way to diagnose this condition while a person is alive. Healthcare providers can suspect a person has it, but there’s no way to confirm it without an autopsy. CTE also has strong similarities and shares symptoms with several other degenerative brain diseases, such as Alzheimer’s disease and frontotemporal dementia.


Symptoms and Causes

What are the symptoms of chronic traumatic encephalopathy?

The symptoms of CTE tend to develop slowly and get worse over time.

Common symptoms of CTE can include:

Other symptoms that can occur include:

What causes chronic traumatic encephalopathy?

CTE happens because of a combination of factors. These factors include:

  • A history of repeated head injuries. The most widely known factor contributing to CTE is a history of repeated head impacts. A person doesn’t have to lose consciousness (also known as being “knocked out”) from these impacts. Instead, the effects of repeated head impacts accumulate over time. That can cause a person to develop CTE.
  • Buildup of faulty proteins in your brain. Your body uses proteins, which are complex chemical molecules, for a wide variety of reasons. One of these proteins, tau (named for a Greek letter), is important in your brain. The tau protein also plays a major role in the development of CTE. A key part of how proteins work is their shape. Your cells can only use a protein if it has the right shape, similar to how a lock needs a correctly shaped key. However, if a protein becomes altered, it’ll malfunction and can potentially spread and affect other areas of the brain. Identifying an altered form of the tau protein in a specific pattern in the brain is the way CTE is currently diagnosed.


Diagnosis and Tests

How is chronic traumatic encephalopathy diagnosed?

There’s no conclusive way to diagnose CTE while a person is alive. The only way to do that is to examine samples of a person’s brain under a microscope, which is only possible during an autopsy after death.

While experts may not be able to confirm CTE before death, they can still make a presumptive diagnosis based on your symptoms and a physical and neurological exam. They’ll also review your history of head injuries and recommend certain lab and imaging tests. The most common tests don’t diagnose CTE. Instead, they rule out other conditions. They include:

Management and Treatment

How is chronic traumatic encephalopathy treated, and is there a cure?

There’s no cure for CTE. Treatments for some of the symptoms are possible, and these vary depending on your symptoms, medical history and more. In addition, there are a number of habits you can incorporate in your lifestyle that helps brain health in general. Your healthcare provider is the best person to tell you about the treatments they recommend and why.


Can I reduce my risk of developing chronic traumatic encephalopathy or prevent it entirely?

Reducing the number of head impacts you experience is ultimately the best way to reduce the risk of CTE. In addition, there are simple measures that can reduce the chance of having a concussion, where blows to the head can cause notable symptoms:

  • Play safely. Wear the appropriate safety gear when playing contact sports like American football or ice hockey. Helmets and other forms of safety gear can reduce the risk of having a concussion. Playing conscientiously and avoiding situations where you could cause a dangerous collision or put yourself at risk for one is also important.
  • Don’t play while hurt. If you take a hit but don’t lose consciousness, it’s easy to brush it off and say you’re fine. However, you don’t have to pass out to have a concussion, and taking another hit after being concussed can be dangerous.
  • Wear a helmet when you’re on your wheels. People who enjoy cycling, rollerblading, skateboarding and similar sports should always wear a helmet. They can make an enormous difference in preventing concussions.
  • Wear your seat belt. Motor vehicle crashes are a common cause of concussions for nonathletes. Wearing your seatbelt can reduce the chances of having a concussion or limit the severity if you still have one.

Outlook / Prognosis

What can I expect if I have chronic traumatic encephalopathy?

As noted earlier, CTE is a degenerative brain disease. That means it’s progressive, and the symptoms will get worse over time. This can take years or even decades. Experts currently don’t have a way to predict how long it may take to see the decline in brain function.

How long does chronic traumatic encephalopathy last?

CTE is a permanent, lifelong condition.

What’s the outlook for this condition?

Currently, the available research and understanding of CTE indicate this condition isn’t deadly on its own. Instead, it causes other health concerns that negatively affect your health and well-being. This includes a gradual loss of the ability to feed, bathe or dress yourself. People with these issues often need to live in a long-term care or skilled nursing facility staffed 24/7 with medical personnel.

When the effects of this condition get severe enough, it can lead to dysphagia, which is when you have trouble swallowing. That can increase your risk of developing pneumonia or respiratory failure.

Living With

How do I take care of myself?

In the earlier stages of this condition, it’s possible to care for yourself with the guidance of a healthcare provider. They can advise you on treating and managing your symptoms and what you can do with your lifestyle to adapt. As this condition worsens, taking care of yourself may become more difficult. Unfortunately, that means you may not be able to live independently after symptoms reach a certain point.

How can I ensure my wishes are followed when I can’t choose myself?

If you have an early diagnosis of CTE (or any other kind of degenerative brain disease), you should talk to your healthcare provider, your family or loved ones, and anyone you trust to make important decisions for you. These discussions are important because they can guide caregivers and loved ones on what you want for yourself if the time comes when you can’t choose for yourself.

These conversations may feel difficult, uncomfortable or unpleasant. Despite that, you should have them and do so sooner rather than later. That helps your loved ones know ahead of time what you want for yourself when you can no longer make those choices. It also means your loved ones don’t have to guess what you want.

In addition to those conversations, you should put your wishes and decisions in writing. That includes preparing documents connected to legal issues and what happens if you can’t care for yourself or make decisions for your care or well-being. Many people consult an attorney to prepare these documents, but you may be able to prepare some on your own (you may need a notary or other official to endorse them, depending on the laws in your area).

When should I see my healthcare provider?

You should see a healthcare provider if you notice any symptoms of problems with your ability to think, remember or concentrate or if there are changes in your mood or behavior.

When should I go to the ER?

You should get immediate help if you have thoughts about harming yourself, including thoughts of suicide, or about harming others. You should also seek immediate help if you suspect someone you know is in imminent danger of harming themselves.

To get help in these situations, you can call any of the following:

  • Suicide and Crisis Lifeline (United States). This line can help people who are struggling with suicidal thoughts or impulses. To call this line, dial 988.
  • Local crisis lines. Mental health organizations and centers in your area may offer resources and help through crisis lines if you’re struggling with thoughts of suicide, self-harm or harming others.
  • 911 (or your local emergency services number). You should call 911 (or the local emergency services number) if you feel like you are (or someone you know is) in immediate danger of self-harm or suicide. Operators and dispatchers for 911 lines can often help people in immediate danger because of a severe mental crisis and send first responders to assist.

Additional Common Questions

What is the difference between post-concussion syndrome and chronic traumatic encephalopathy?

People sometimes use the terms “post-concussion syndrome (PCS)” and “chronic traumatic encephalopathy” interchangeably, but these aren’t the same condition.

  • PCS: This condition you develop after having a concussion. It can last weeks or months, but goes away as your brain recovers from the injury. Chronic post-concussive syndrome is a long-term form of this condition, but it doesn’t involve unusual accumulations of tau protein in the brain.
  • CTE: This is a permanent degenerative brain disease (meaning it gets worse over time).

A note from Cleveland Clinic

Chronic traumatic encephalopathy (CTE) is a condition that can affect people who have a history of repeated head impacts or concussions. It typically takes years or even decades to develop. This condition falls under degenerative brain diseases, which means it progressively damages your brain over time. Unfortunately, it’s incurable and permanent.

While there’s no cure, there are many things you can do to prevent it. Avoiding significant, repeated blows to the head is key, especially by using safety gear and safe practices while participating in contact sports or activities with a greater risk of head injury. Research is also ongoing for this condition, and experts are continuing to unravel how this condition happens and possible treatments that could offer hope to people in years to come.

Medically Reviewed

Last reviewed on 12/09/2022.

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