Diseases and Conditions
Chronic traumatic encephalopathy

Updated: 4/20/2016


Chronic traumatic encephalopathy (CTE) is the term used to describe brain degeneration likely caused by repeated head traumas. CTE is a diagnosis only made at autopsy by studying sections of the brain.

CTE is a very rare condition. It has been found in the brains of people who played contact sports, such as football, as well as others. Some symptoms of CTE are thought to include difficulties with thinking (cognition), physical problems, emotions and other behaviors.

CTE is a very controversial condition that is still not well-understood. Researchers do not yet know the frequency of CTE in the population and do not understand the causes. There is no cure for CTE.


Some of the possible signs and symptoms of CTE may include:

  • Difficulty thinking (cognitive impairment)
  • Impulsive behavior
  • Depression or apathy
  • Short-term memory loss
  • Difficulty planning and carrying out tasks (executive function)
  • Emotional instability
  • Substance abuse
  • Suicidal thoughts or behavior

Other suspected symptoms may include:

  • Irritability
  • Aggression
  • Speech and language difficulties
  • Motor impairment, such as difficulty walking, tremor, loss of muscle movement, weakness or rigidity
  • Trouble swallowing (dysphagia)
  • Vision and focusing problems
  • Trouble with sense of smell (olfactory abnormalities)
  • Dementia

The full list of symptoms of people with CTE at autopsy is still unknown. It is unclear what kind of symptoms, if any, it may cause. Little is known right now about how CTE progresses.

When to see a doctor

CTE is thought to develop over many years after repeated brain injuries (mild or severe). However, see your doctor in case of the following:

  • Suicidal thoughts. Research shows that people with CTE may be at increased risk of suicide. If you have thoughts of hurting yourself, call 911, your local emergency number or the National Suicide Prevention Lifeline at 800-273-TALK (800-273-8255).
  • Head injury. See your doctor if you have had a head injury, even if you didn't need emergency care. If your child has received a head injury that concerns you, call your child's doctor immediately. Depending on the signs and symptoms, your doctor may recommend seeking immediate medical care.
  • Memory problems. See your doctor if you have concerns about your memory or other thinking (cognitive) or behavior problems.
  • Personality or mood changes. See your doctor if depression, anxiety, aggression or impulsivity occur.


Initial injury

Repetitive head trauma is likely the cause of CTE. Football players have been the focus of most CTE studies.

However, athletes participating in other sports, including soccer, ice hockey, rugby, boxing, wrestling, basketball, field hockey, cheerleading, volleyball and lacrosse, may experience repeated head impacts and also have high rates of concussion.

CTE has also been found in people who repeatedly bang their heads, people who have been physically abused, and those with epilepsy that has not been well-controlled. Blast injuries to military personnel also can result in CTE.

However, not all athletes and not everyone who experiences repeated concussions, including military personnel, go on to develop CTE. Some studies have shown no increased incidence of CTE in people exposed to repeated head injuries.

Effect of injury

CTE is thought to cause areas of the brain to waste away (atrophy). Injuries to the section of nerve cells that conduct electrical impulses affect communication between cells.

It's possible that people with CTE may show signs of another neurodegenerative disease, including Alzheimer's disease, amyotrophic lateral sclerosis (ALS) — also known as Lou Gehrig's disease — Parkinson's disease or frontotemporal lobar degeneration — also known as frontotemporal dementia.

Risk factors

Repeated exposure to traumatic brain injury is thought to increase the risk of CTE, but experts are still learning about the risk factors.

Preparing for your appointment

You'll probably start by seeing your family doctor or general practitioner, who may refer you to a neurologist, psychiatrist, neuropsychologist or other specialist for further evaluation.

Because appointments can be brief and there's often a lot to discuss, prepare before your appointment.

What you can do

  • Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance. Ask if you need to fast for blood tests.
  • Write down any symptoms, including any that may seem unrelated to the reason for scheduling the appointment. Your doctor will want to know details about your concern for your mental function. Try to remember when you first started to suspect that something might be wrong. If you think your difficulties are getting worse, be ready to explain why, and be prepared to discuss specific examples.
  • Write down key personal information, including any major stresses or recent life changes.
  • Make a list of all medications, vitamins or supplements that you're taking.
  • Make a list of your other medical conditions, including those you are currently being treated for, such as diabetes or heart disease, and those you've had in the past, such as strokes.
  • Take a family member, friend or caregiver along, if possible. Sometimes it can be difficult to soak up all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.

Preparing a list of questions will help make the most of your time with the doctor. Prioritize questions from most important to least important. Some basic questions to ask the doctor include:

  • What is likely causing symptoms?
  • Are there other possible causes for symptoms?
  • What kinds of tests are needed?
  • Is my condition likely temporary or chronic? How will it likely progress over time?
  • What's the best course of action?
  • What are the alternatives to the primary approach being suggested?
  • I have other medical issues. How can they be managed together?
  • Are there any clinical trials of experimental treatments I should consider?
  • Are there any restrictions?
  • If medication is being prescribed, is there a potential interaction with other medications I am taking?
  • Are there any brochures or other printed material that I can take home with me? What websites do you recommend?
  • Do I need to see a specialist? What will that cost, and will my insurance cover it? You may need to call your insurance provider for some of these answers.

If you've had a concussion, some basic questions to ask your doctor include:

  • What is the risk of future concussions?
  • When will it be safe to return to competitive sports?
  • When will it be safe to resume vigorous exercise?
  • Is it safe to return to school or work?
  • Is it safe to drive a car or operate power equipment?

Don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor

The doctor may ask you a variety of questions.

Questions related to symptoms:

  • What symptoms are you experiencing? Any trouble finding words or remembering events, focus, personality changes, or getting lost?
  • When did symptoms begin?
  • Are symptoms steadily worsening, or are they sometimes better and sometimes worse?
  • How severe are symptoms?
  • Have you stopped doing certain activities, such as managing finances or shopping, because of difficulty thinking through them?
  • What, if anything, seems to improve or worsen symptoms?
  • Have you noticed any changes in the way you tend to react to people or events?
  • Do you have more energy than usual, less than usual or about the same?
  • Have you noticed any trembling or trouble walking?

Questions related to health history:

  • Have you had your hearing and vision tested recently?
  • Is there a family history of dementia or other neurological disease such as Alzheimer's, ALS or Parkinson's disease?
  • What medications are you taking? Are you taking any vitamins or supplements?
  • Do you drink alcohol? How much?
  • What other medical conditions are you being treated for?

If you've had a concussion, your doctor may ask questions related to events surrounding injury:

  • Have you had any previous head injuries?
  • Do you play contact sports?
  • How did you get this injury?
  • What symptoms did you experience immediately after the injury?
  • Do you remember what happened right before and after the injury?
  • Did you lose consciousness after the injury?
  • Did you have seizures?

Questions related to physical signs and symptoms:

  • Have you experienced nausea or vomiting since the injury?
  • Have you been experiencing headaches? How soon after the injury did the headaches start?
  • Have you noticed any difficulty with physical coordination since the injury?
  • Have you noticed any sensitivity or problems with your vision and hearing?
  • Have you noticed changes in your sense of smell or taste?
  • How is your appetite?
  • Have you felt lethargic or easily fatigued since the injury?
  • Are you having trouble sleeping or waking from sleep?
  • Do you have any dizziness or vertigo?

Questions related to cognitive or emotional signs and symptoms:

  • Have you had any problems with memory or concentration since the injury?
  • Have you had any mood changes, including irritability, anxiety or depression?
  • Have you had any thoughts about hurting yourself or others?
  • Have you noticed or have others commented that your personality has changed?
  • What other signs or symptoms are you concerned about?

Tests and diagnosis

There is currently no reliable way to diagnose CTE. A diagnosis requires evidence of degeneration of brain tissue and deposits of tau and other proteins in the brain that can be seen only upon inspection after death (autopsy). Some researchers are actively trying to find a test for CTE that can be used while people are alive. Others continue to study the brains of deceased individuals who may have had CTE, such as football players.

Eventually, the hope is to use a range of neuropsychological tests, brain imaging and biomarkers to diagnose CTE. In particular, imaging of amyloid and tau proteins will aid in diagnosis.

Neurological tests

Your doctor will check your neurological health by testing your:

  • Speech, language and cognition — including short- and long-term memory
  • Reflexes
  • Muscle tone and strength
  • Ability to get up from a chair and walk across the room
  • Sense of sight and hearing
  • Coordination
  • Balance

Brain-imaging tests

Brain-imaging technology is currently used to diagnose mild traumatic brain injury. Some of the following technologies might be used for CTE diagnosis in the future.

Magnetic resonance imaging (MRI). An MRI uses a strong magnetic field to detail brain images. Researchers believe that as the following specialized MRI tests improve, they may be able to help diagnose CTE.

  • Susceptibility-weighted imaging (SWI) is a type of MRI that shows tiny bleeds (hemorrhages) that result from injury to the central nervous system.
  • Diffusion tensor imaging (DTI) is a type of MRI that reveals the movement of water and the path of white matter in the brain, which can show brain abnormalities. It shows promise for detecting CTE, but needs to become more accurate and precise.
  • Magnetic resonance spectroscopy (MRS) is similar to MRI but may be able to provide greater details about neurological damage.

Positron emission tomography (PET). A PET scan uses a low-level radioactive tracer that is injected in a vein. Then, a scanner tracks the tracer's flow through the brain. Researchers are actively working to develop PET markers to detect tau abnormalities associated with neurodegenerative disease.

The goal is to develop a marker to identify the tau pathology of CTE in people who are living.

Researchers are using various substances that bind to tau and other proteins on PET scans. These PET scans are in the research phase and not available for clinical testing.

Event-related potentials (ERPs) and quantitative EEG. These noninvasive tests use electroencephalography (EEG), in which a mesh cap covered with electrodes is placed on a person's head. It allows doctors to detect, record and analyze brain waves, which may find brain changes that result from multiple traumatic brain injuries.

Single-photon emission computerized tomography (SPECT). SPECT is an imaging test used to diagnose types of dementia. Studies are needed to show whether SPECT can tell CTE from Alzheimer's disease or other neurodegenerative diseases.

Other tests

There's been little research on plasma or cerebral spinal fluid to diagnose the long-term disease processes of CTE. Some biomarkers that are used in Alzheimer's disease research may be useful for CTE because the conditions are similar. These biomarkers would need to identify brain degeneration from CTE separately from the original brain trauma.

Treatments and drugs

CTE is a progressive, degenerative brain disease for which there is no treatment. More research on treatments is needed, but the current approach is to prevent head injury. It's also important to stay informed about the latest recommendations for detecting and managing traumatic brain injury.

If you had a concussion recently, you will not have developed CTE. However, you should take care of yourself until you have fully recovered in order to prevent additional injury. If your symptoms return at any point:

  • Cut back on activities
  • Get plenty of rest
  • Reduce physical activity if it increases your symptoms
  • Avoid too much computer time if this increases your symptoms
  • Get plenty of sleep
  • Return to activities gradually, with guidance from your doctor
  • Avoid drinking alcohol and take only prescribed medication
  • Write things down or limit tasks, as needed
  • Ease back into work
  • Consult others before making major decisions

It is especially important to avoid a second concussion before the first one heals (second impact syndrome). A second concussion can result in permanent brain damage or death.

If you are caring for someone who has symptoms of CTE, he or she may benefit from supportive care similar to that of people with dementia.

  • Calming environment. Reducing clutter and distracting noise can make it easier for someone with dementia to focus and function. It may also reduce confusion and frustration.
  • Reassuring responses. A caregiver's response can worsen behaviors such as agitation. Avoid correcting and quizzing a person with dementia. Offer reassurance and validate his or her concerns.
  • Modified tasks. Break tasks into easier steps and focus on success, not failure. Create structure and routine during the day to reduce confusion.
  • Regular exercise. A daily 30-minute walk can improve mood and maintain the health of joints and muscles, including the heart. Exercise can also promote restful sleep, prevent constipation, lessen symptoms of depression, help retain motor skills and create a calming effect. Try a stationary bike or chair exercises if walking is difficult.
  • Games and thinking activities. Encourage games, crossword puzzles and other activities that use thinking (cognitive) skills to help slow mental decline.
  • Nighttime rituals. Behavior is often worse at night. Establish calming bedtime rituals that are separate from the noise of television, meal cleanup and active family members. Leave night lights on to prevent disorientation.


There is no treatment for CTE. But CTE may be prevented because it is associated with recurrent concussions. Individuals who have had one concussion are more likely to have another head injury. The current recommendation to prevent CTE is to reduce mild traumatic brain injuries and prevent additional injury after a concussion.

The following equipment can help reduce head injury:

  • Sports-specific helmets. Helmets have reduced injury for baseball, ice hockey, rugby, alpine skiing and snowboarding. It's possible that people choosing to wear a helmet also take fewer risks. Helmets have not reduced injury for soccer players. Helmets also cannot eliminate the occurrence of concussions.
  • Bicycle and motorcycle helmets. These reduce head injury in case of accident.

Coaches and players need to understand current guidelines for sports-related injuries. It's difficult to evaluate concussion during play, and coaches and players should be cautious and keep injured athletes out of the game.

The following signs and symptoms of concussion may be visible to coaches or to the athlete.

Danger signals:

  • Loss of consciousness, even briefly
  • One pupil larger than the other
  • Drowsy or cannot be awakened
  • A headache that gets worse
  • Weakness, numbness or decreased coordination
  • Repeated vomiting or nausea
  • Slurred speech
  • Convulsions or seizures
  • Unable to recognize people or places
  • Increasingly confused, restless or agitated or has other unusual behavior

Signs of concussion someone might observe in another person:

  • Appears dazed or stunned
  • Is confused about assignment or position
  • Forgets an instruction
  • Is unsure of game, score or opponent
  • Moves clumsily
  • Answers questions slowly
  • Loses consciousness, even briefly
  • Shows mood, behavior or personality changes
  • Can't recall events prior to or after hit or fall

Symptoms of concussion someone might notice themselves:

  • Headache or pressure in head
  • Nausea or vomiting
  • Balance problems or dizziness
  • Double or blurry vision
  • Sensitivity to light
  • Sensitivity to noise
  • Feeling sluggish, hazy, foggy or groggy
  • Concentration or memory problems
  • Confusion

If you suspect a concussion in yourself or someone else, follow the four-step action plan:

  • Remove the athlete from play for the day.
  • Have a health care professional evaluate the athlete.
  • Inform the athlete's parent, guardian or significant other.
  • Keep the athlete out of play until health care professional OKs a return.

Follow the gradual five-step plan to return to play:

  1. Light aerobic exercise, no weightlifting
  2. Moderate exercise, weightlifting OK
  3. Heavy, noncontact exercise
  4. Practice and controlled full contact
  5. Competition

Content from Mayo Clinic