Chronic Traumatic Encephalopathy

Overview

Chronic traumatic encephalopathy (CTE) is a progressive brain condition that has been associated with repeated head impacts over a long period. It is most commonly discussed in connection with contact sports such as boxing, American football, and ice hockey, as well as military service involving blast exposure. These repeated impacts, including ones that may not have caused obvious concussions, are thought to contribute to gradual changes in the brain.

CTE is associated with the buildup of an abnormal form of a protein called tau in the brain, which damages brain cells over time. Importantly, CTE can currently be confirmed only by examining brain tissue after death, so it cannot be definitively diagnosed in a living person. Researchers continue to study who develops CTE, why, and how to recognize and prevent it.

Symptoms

Symptoms thought to be associated with CTE usually develop years or even decades after the period of repeated head impacts. They can affect mood, behavior, thinking, and movement, and may include:

• Changes in mood, such as depression or hopelessness
• Irritability, aggression, or impulsive behavior
• Problems with memory and concentration
• Difficulty with planning, organizing, and decision-making
• Confusion that worsens over time
• Problems with movement, balance, or coordination in some people
• In some cases, suicidal thoughts

If you or someone you know is having thoughts of self-harm or suicide, treat it as an emergency: call or text a suicide and crisis helpline, contact emergency services, or go to the nearest emergency department right away. These symptoms can have many causes and deserve prompt evaluation.

Causes

CTE is associated with repeated head impacts over time. The likely contributors include:

• Repeated head impacts: Many years of repeated blows to the head, including from contact sports and combat training, even when individual hits did not cause noticeable concussions.
• Tau protein buildup: These impacts are linked to the accumulation of an abnormal form of tau protein that disrupts and damages brain cells.

Not everyone exposed to repeated head impacts develops CTE, and the exact reasons some people do and others do not are still being studied. The total amount of head impact exposure over time appears to matter more than any single injury.

Risk Factors

• Many years of participation in contact or collision sports
• A history of repeated concussions or head impacts
• Military service with exposure to blast injuries
• Occupations or activities with frequent head trauma
• A longer duration of exposure to head impacts

Diagnosis

CTE currently cannot be definitively diagnosed during life. The diagnosis is confirmed only by examining brain tissue after death. In living people, doctors focus on evaluating symptoms and ruling out other treatable conditions:

• Detailed history: Including the history of head impacts and the pattern of symptoms over time.
• Neurological and cognitive testing: To assess memory, thinking, mood, and movement.
• Brain imaging: MRI or other scans to look for other causes and changes, though no scan can confirm CTE.
• Excluding other conditions: Checking for depression, other forms of dementia, and medical conditions that can cause similar symptoms.

Research is ongoing to develop reliable ways to identify CTE in living people.

Treatment

There is no cure for CTE and no treatment to reverse the underlying brain changes. Care focuses on managing symptoms and supporting quality of life:

• Treating mood and behavior symptoms: Counseling, therapy, and medications for depression, anxiety, irritability, or impulsivity.
• Cognitive support: Strategies and structure to help with memory and daily functioning.
• Safety and support: Help for families and caregivers, and addressing risks related to mood and behavior.
• Mental health crisis care: Prompt help for any thoughts of self-harm or suicide.

Because many symptoms overlap with treatable conditions such as depression, getting a thorough evaluation is important, since some symptoms may improve with appropriate treatment.

Prevention

Reducing exposure to repeated head impacts is the main way to lower risk:

• Follow concussion protocols and allow full recovery before returning to play
• Reduce unnecessary head impacts in training and practice
• Use proper technique and well-fitted protective equipment in sports
• Support rule changes and coaching that limit head contact, especially for children and youth
• Take any concussion seriously and seek medical guidance

When to See a Doctor

See a doctor if you or someone with a history of repeated head impacts develops ongoing changes in mood, memory, thinking, or behavior. These symptoms have many possible causes, several of which are treatable, so evaluation is worthwhile. Seek emergency help right away if there are:

• Thoughts of suicide or self-harm
• Sudden, severe confusion or agitation
• Risk of harm to oneself or others

For thoughts of suicide, call or text a crisis helpline, call emergency services, or go to the nearest emergency department immediately.

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). Traumatic brain injury and concussion.
2. Mayo Clinic. Chronic traumatic encephalopathy.
3. National Institute of Neurological Disorders and Stroke (NINDS). Traumatic brain injury.
4. MedlinePlus, U.S. National Library of Medicine. Traumatic brain injury.