Chronic traumatic encephalopathy (CTE) is a brain disease found in people who have had repeated head injuries. It can lead to physical and mental problems that get worse over time.


Repeated head injuries can lead to a buildup of a protein called tau. These proteins create tangled masses in the brain. This causes changes in how the brain works.

Risk Factors

This risk of this problem is higher in people who have had past head injuries. The risk may be higher in people who:

  • Played contact sports, such as boxing, football, hockey, wrestling, and soccer
  • Were in military combat
  • Were physically abused
  • Have had seizures
  • Have a developmental disability and harm themselves (head banging)


Problems may start many years after the head injuries. They also vary from person to person. A person may have:

  • Memory problems
  • Confusion
  • Problems with focus
  • Poor decision making, such as acting without thinking
  • Mood changes, such as irritability and aggression,
  • Lack of interest in activities
  • Believing things that are not based in reality

People with severe problems may have signs of depression, such as feelings of hopelessness and suicidal thoughts.


The doctor will ask about your symptoms and health history. A physical exam will be done. You will be asked about any past head injuries. This may be enough to suspect the diagnosis.

These tests may be done to learn more about the brain:

The only way to diagnose CTE is for a doctor to look at the brain after a person has died.

CT Scan of the Head
Breast self-exam, step 5

Copyright © Nucleus Medical Media, Inc.


Researchers are looking for ways to treat CTE. Problems may be managed with:


People who have had a past head injury should wait to return to sports until the doctor says it is safe.

The risk of this problem may also be lowered by taking steps to avoid head injury, such as:

  • Wearing a seatbelt in motor vehicles
  • Using safe, age-based sports methods for children
  • Wearing a helmet when:
    • Playing a contact sport like football, soccer, or hockey
    • Riding a bike or motorcycle
    • Using skates, scooters, and skateboards
    • Catching, batting, or running bases in baseball or softball
    • Riding a horse
    • Skiing or snowboarding

Boston University Center for Traumatic Brain Injury

Concussion Legacy Foundation


Health Canada

Ontario Brain Injury Association


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Last reviewed December 2020 by EBSCO Medical Review Board Rimas Lukas, MD  Last Updated: 1/22/2021