1 What is Chronic Traumatic Encephalopathy?

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disorder that results from repetitive concussions (mild traumatic brain injury).

It is characterized by progressive neuron damage, which can be detected by imaging tests. The condition can affect thinking ability, emotions, and behavior. Repeated head injuries cause a gradual degeneration in brain function. It results in concussions both with and without symptoms. Symptoms start slowly and creep up on the patient. Months or even years after the initial symptoms have faded, new symptoms may occur. The term “encephalopathy” is derived from ancient Greek. It is a brain-damaging condition that occurs as a result of traumatic impacts to the head, and persists over a period of years or decades. A brain affected by CTE gradually deteriorates and loses mass over time. Certain areas of the brain are prone to becoming enlarged, and others are liable to atrophy.

The signs and symptoms appear years after the injury. However,  you may not develop CTE even if you have had one or more concussions.

Unfortunately, CTE is diagnosed only after death by visually examining the brain in an autopsy; there is no diagnostic test for CTE in living individuals.

People who experience repetitive head injuries, such as athletes, are at risk of developing CTE. The condition is also more likely to occur in war veterans who have suffered blast injuries.

A critical brain protein called tau helps stabilize and support certain structures within brain cells. In CTE, there is a build-up of abnormal tau, setting off a chain reaction due to the misfolded tau released in the cell. This reaction causes it to clump together, which then kills the neurons and clumps spread to the nearby cells. Even after the brain trauma is healed, these changes still continue in the brain.

Potential signs of CTE are personality changes, behavioral changes like aggression and depression, problems with thinking, confusion, impaired judgment, control problems, progressive dementia, and memory problems.

The causes of CTE are still unknown, and there are no treatments for it.

2 Symptoms

Symptoms of CTE are similar to other neurodegenerative conditions, such as Alzheimer's disease, Parkinson's disease, FrontotemporalHYPERLINK "https://www.findatopdoc.com/Medical-Library/Diseases-and-Conditions/Frontotemporal-Dementia" dementia, and Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease.

People with CTE initially experience impaired thinking (cognition), impulsive mood, and behavioral changes. As the disease progresses, they develop physical problems. Repeated brain injury can also cause Post-traumatic stress disorder in military personnel.

Signs and symptoms, which take years after recurrent traumatic brain injury to become apparent, include:

  • Decreased thinking ability (cognitive impairment)
  • Acting without thinking (impulsive behavior)
  • Depression or reduced motivation (apathy)
  • Short-term memory loss
  • Difficulty planning and carrying out tasks (executive function)
  • Emotional instability
  • Abuse of alcohol and other drugs
  • Thoughts of suicide

Memory and executive functions deteriorate as the disease advances. Other symptoms include:

  • Short temper
  • Aggressive behavior
  • Problems with speech and language
  • Impaired physical conditions, such as difficulty walking, tremors, loss of muscle movement, weakness, or rigidity
  • Difficulty swallowing
  • Vision and focusing problems
  • Impaired sense of smell (olfactory abnormalities)

Progression of CTE symptoms is described by different stages:

  • Stage I: Headache, problems with concentration or focus
  • Stage II: Depression, violent behavior, and short-term memory loss
  • Stage III: Impaired thinking and decision-making ability (executive and cognitive impairment)
  • Stage IV: Dementia, word-finding difficulty, and aggression

Pathological changes in the brain due to CTE continue for a prolonged period of time after the original brain injury or even after retirement from the sport.

CTE progression varies among younger and older individuals. In younger people, it affects behavior and mood, whereas in older people, it impairs cognitive ability, which can result in dementia.

It is not clear how the disease progresses or if changes in the process occur as time passes.

CTE symptoms are classified based on whether the problems occur in thinking, mood, or behavior. Symptoms are diagnosed years or even decades after repetitive brain trauma. By this time, the neurodegeneration progresses to a point where these changes begin interfering with daily functioning. Changes in symptoms are initially mild, but progress to a more severe form. Advanced cases of CTE lead to dementia.

  • Thinking (cognitive) problems: Includes difficulties with learning, memory, executive functioning, ability to connect memories, experiences, or behaviors.
  • Mood changes: These involve suicidal thoughts or behavior, depression, irritability, and loss of motivation.
  • Behavioral changes: These include problems with impulse control, and can lead to violent, aggressive behavior or even problems with substance abuse.

Symptoms may have life-changing effects and may be mistaken for symptoms of the aging process or other conditions, such as Alzheimer’s or Parkinson’s disease. CTE was diagnosed in the suicides of NFL player Junior Seau and professional wrestler Chris Benoit, who committed suicide after murdering his wife and son.

Underlying genetics of this disorder are not known. However, not everyone with a history of repetitive brain trauma develops CTE, which suggests there may be a genetic susceptibility. While genes may play a role, it is still a mystery why some individuals who receive repetitive brain injuries from contact sports develop CTE while others do not. One such possibility is having the APOE4 allele, which may be why some football players develop neurodegenerative diseases while others do not. More research is needed in this area, though, along with investigations into the aggregate of tau genes to determine whether having a particular genetic profile makes a person susceptible to CTE.

Visit your doctor if you have:

  • Suicidal thoughts
  • A recent head injury, which needs immediate medical care. If your child's head injury worries you, visit the child's doctor immediately. The doctor may recommend immediate medical care depending on the signs and symptoms.
  • Memory problems or other thinking (cognitive) or behavioral problems. If you think you have dementia or you are worried about your memory, see your general practitioner. Encourage others if you are worried about them. Memory problems may also be caused by depression, medications, stress, and other health issues. The doctor will perform simple tests to find the cause and may refer a specialist if needed.
  • Personality or mood changes, such as feeling depressed, anxious, aggressive, or impulsive.

3 Causes

In the military, blast injuries may cause chronic traumatic encephalopathy. However, not every person or athlete experiencing recurrent blows to the head develops CTE.

CTE can cause atrophy (deterioration) of many parts of the brain. Damage to axons (part of nerve cells that conduct electrical impulses) of the neuron interrupts cell-to-cell communication.

Physical evidence that revealed the connection between football and CTE was first discovered by Bennet Omalu, M.D—a forensic neuropathologist. He performed an autopsy on Mike Webster, the Hall of Fame center for the Pittsburgh Steelers. Previously, CTE was connected to boxing and was called “punch-drunk syndrome.” A close relation was found between CTE and the number of rounds boxed, rather than the number of times a boxer was knocked out. This suggested that repeated blows to the head which do not result in unconsciousness may also increase the risk.

CTE is common among those playing:

  • Football
  • Ice hockey
  • Rugby
  • Boxing
  • Wrestling
  • Basketball
  • Field hockey
  • Cheerleading
  • Volleyball
  • Lacrosse

Deposition of tau and TDP-43 proteins as well as changes in white matter (that consists of nerve fibers) might occur. Deposition of beta-amyloid, a protein, is rare in CTE, while common in Alzheimer's disease.

More than one-third of people with CTE experience signs of neurodegenerative (degeneration of neurons, especially in the brain) disease, such as:

People who bang their head, who have been physically abused, or who have epilepsy not well-controlled are also at risk. 

4 Making a Diagnosis

For researchers and physicians, CTE is a new area of exploration, so formal clinical guidelines for diagnosis and management do not exist yet. It is tough to make a diagnosis, as there are no major abnormalities visible on imaging scans. CTE and other neurodegenerative conditions have many features in common, thus, there is no diagnostic test for chronic traumatic encephalopathy. Diagnosis is based on symptoms and clinical features. The general practitioner will ask about the problem and perform a few simple tests like physical or mental tasks to help the diagnosis. Diagnosis of CTE is achieved by confirming degeneration of brain tissue and deposition of tau and other proteins in the brain. It can be detected upon visual inspection of the brain after death in an autopsy. Diagnostic tests for CTE for living people are still being researched. The changes in the brain that occur due to CTE are different from the ones found in Alzheimer’s disease. However, in both conditions, the brain shrinks, and there is a presence of neurofibrillary tangles, which contain tau.

Scientists are still working on CTE and finding ways to identify it in the living. Some researchers study the brains of dead people who were likely to have CTE. Currently, neuropsychological tests, brain imaging, and biomarkers are used in the hopes of diagnosing CTE. Imaging of amyloids and tau can help with a diagnosis as well.

Your primary caregiver will refer you to a neurologist, psychiatrist, neuropsychologist, or other specialist for additional examination.

How to Prepare Yourself for the Visit

Preparing for the doctor’s visit can optimize therapy and make the consultation more fruitful. List out all symptoms, and write down your key medical information, as well as the names of all your medications, vitamins, and supplements. Ask a friend or a family member to accompany you to the visit.

Make a list of questions to ask your doctor. Some typical questions include:

  • What could be the possible causes of my symptoms?
  • What tests are needed?
  • How long will my condition last?
  • Are there any alternatives to the primary approach suggested?
  • Can I participate in clinical trials for experimental treatments, if any?
  • Do I need to follow any restrictions?
  • Do I need to see a specialist?

If you've had a recent blow to the head, you may want to ask:

  • Am I likely to have future concussions?
  • When can I return to competitive sports?
  • When can I resume vigorous exercise?
  • Is resuming my sport safe?
  • Can I drive a car or operate power equipment?

An honest talk with your doctor can optimize therapy and improve the outcome. Prepare yourself to answer some essential questions from your doctor.

Your doctor might ask you typical questions like:

  • What are your symptoms and how severe are they?
  • When did you start noticing the symptoms?
  • How would you describe the changes in pattern of your symptoms?
  • Do you fear doing tasks that require serious thinking, like managing finances or shopping?
  • Does anything improve or worsen your symptoms?
  • How would you describe the changes in your response to people or events?
  • Is there any change in your energy level?
  • Do you tremble or have problems walking?
  • How are your vision and hearing?
  • Does anyone in your family suffer from dementia or another neurological disease, such as Alzheimer's, ALS, or Parkinson's disease?
  • Can you provide a list of medications you are currently taking?
  • Do you drink alcohol? If yes, how often?
  • Have you been diagnosed with other medical conditions?

If you've had a concussion recently, your doctor is likely to ask:

  • Do you have a personal history of head injuries?
  • Are you an athlete? If yes, what sport?
  • How did you sustain this injury?
  • Do you remember your symptoms 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?
  • How often have you had nausea or vomiting since the injury?
  • Do you have headaches? If yes, when did they start?
  • Have you experienced difficulty with physical coordination since the injury?
  • Have you experienced vision or hearing problems since the injury?
  • Has your sense of smell or taste changed after the injury?
  • How have your energy levels changed since the injury?
  • Do you have any sleep issues?
  • Do you have any dizziness or vertigo?

Questions related to cognitive or emotional symptoms include:

  • How has the injury affected your memory or concentration?
  • Have you experienced any mood changes, including irritability, anxiety, or depression?
  • Have you had any violent thoughts about self-harm?
  • Has anyone near you commented about changes in your personality after the injury?

Neurological Tests

Your neurological health is evaluated by testing:

  • Your speech, language, and cognition, as well as short- and long-term memory
  • Your immediate response to stimuli, or reflexes
  • Muscle tone and strength
  • Whether you can get up from a chair and walk around
  • Sense of sight and hearing
  • Balance
  • Whether you can effectively perform complex activities

Brain-Imaging Tests

Imaging tests are used to detect if there are injuries in the brain due to trauma.

Some of the following technologies might be further developed for CTE diagnosis:

  • Magnetic resonance imaging (MRI): An MRI produces detailed pictures of the brain. In the future, continuous improvements in MRI tests may be able to detect CTE.

         Susceptibility-weighted imaging (SWI) is a type of MRI that can reveal micro-hemorrhages that result due to physical injury to the brain.

         Diffusion tensor imaging (DTI) is a type of MRI that can detect changes or disruption in the brain’s white matter. With improvements in      

         accuracy and precision, DTI can be extensively used to diagnose CTE.

         Magnetic resonance spectroscopy (MRS) is similar to MRI, but may provide more detailed information about damage in the brain.

  • Positron emission tomography (PET): A PET scan uses a radioactive tracer, which has a low level of radioactivity. The radioactive tracer is injected into a vein and is continuously tracked by a scanner as it flows through the brain. PET markers that help detect tau abnormalities in living individuals are currently being studied.
  • Event-related potentials (ERPs) and quantitative EEG: In EEG, electrodes are placed on a person's head, and signals are sent to a computer to record brain waves. The brain waves are then examined to see if there are any changes in neurons and the brain. Usually, abnormal wave patterns are seen if a person has had multiple head traumas.
  • Single photon emission computerized tomography (SPECT): SPECT is used to detect different types of dementia.
  • Other tests: Blood, plasma, or cerebral spinal fluid may be tested to detect the progression of CTE over time.

Because Alzheimer's disease and CTE have some similarities, biomarkers used in Alzheimer's disease might also be used for CTE.

5 Treatment

Chronic traumatic encephalopathy is a degenerative disease that progresses with time and has no cure. The only way to prevent it is by avoiding head injuries and managing any mild traumatic brain injury.

Having a recent concussion does not mean you will develop CTE. However, you should be careful to avoid further injury until you have recovered. If you start re-experiencing symptoms, take the following precautions:

  • Reduce physical activity
  • Get plenty of sleep and rest
  • Avoid spending too much time on the computer
  • Under the guidance of your doctor, start physical activities slowly
  • Avoid alcohol
  • Take medications only as recommended
  • Limit tasks
  • Do not hurry back to work

It is very important to avoid a second concussion while you are recovering from a first (second impact syndrome).

A second concussion can permanently damage your brain or even cause death. People with CTE and dementia need similar supportive care, such as:

  • Calming environment: A calm environment helps people with dementia to focus and be responsible. It can also reduce agitation and annoyance.
  • Reassuring responses: Avoid correcting and questioning a person with dementia. Encouraging and agreeing will calm the person.
  • Modified tasks: Simplify tasks and talk about success instead of failure. A routine schedule reduces confusion in people with dementia.
  • Regular exercise: Daily physical activities, for example, thirty-minute walks, boost mood and maintain overall health. Exercise can also induce and maintain sleep, prevent constipation, reduce symptoms of depression, help manage motor skills, and have a calming effect. Someone who has difficulty walking may use a stationary bike.
  • Games and thinking activities: Participating in games that require cognitive skills, such as crossword puzzles, can delay mental decline in people suffering from dementia.
  • Nighttime bed habits: Make sure the person as well as the environment is calm while going to bed, with minimal noise and less active members. Do not turn off the lights without permission.

6 Prevention

Since chronic traumatic encephalopathy can develop from repetitive traumatic injury to the brain, it can be prevented.

Individuals who already had one concussion are at risk of another head injury. CTE can be prevented if traumatic brain injuries are reduced and further injury after a concussion is avoided.

Use of helmets can reduce the incidences of head injury. Different types of helmets include:

  • Sports-specific helmets: Helmets may protect you from injuries while playing baseball, ice hockey, rugby, alpine skiing, and snowboarding. During a contact sport, always wear the recommended protective equipment. Helmets are not effective for soccer players. Also, helmets do not always prevent concussions.
  • Bicycle and motorcycle helmets: These reduce head injury in motor accidents.

Follow the doctor’s advice about returning to play after a concussion.

Any contact sport a child is participating in should be properly supervised by a qualified and trained official.

If any symptoms of a previous head injury return, seek medical advice.

Coaches and players should be kept up to date on the present direction for sports-related injuries. Assessment of concussions during play is not possible, so coaches and players should not allow injured athletes to continue playing.

Coaches or athletes may notice the following signs and symptoms of a concussion:

Danger signals

  • Transient unconsciousness
  • Unequal pupil size
  • Drowsiness or inability to be wakened
  • Aggravating headache
  • Weakness, numbness, or coordination problems
  • Recurrent vomiting or nausea
  • Slow speech that is difficult to understand
  • Seizures
  • Inability to recognize people or places
  • Confusion, restlessness, agitation, or other unusual behavior

You might also notice the following signs in another person: 

  • Appearing bewildered and confused
  • Lacking connection to surroundings
  • Abnormal movement
  • Delayed response to questions
  • Loss of consciousness for a short period of time
  • Changes in mood, behavior, or personality
  • Forgetfulness

You yourself may experience such symptoms as:

  • Severe headache or pressure in the head
  • Nausea or vomiting
  • Balance problems or dizziness
  • Seeing overlapped objects or hazy, out-of-focus objects
  • Sensitivity to light and noise
  • Feeling sluggish, hazy, foggy, or groggy
  • Lack of concentration or memory problems
  • Confusion

The following steps can be helpful if you suspect a concussion in yourself or someone else:

  • Refrain from playing any sports for a day
  • Seek an examination by a healthcare professional
  • Notify parents, guardian, or significant other about the concussion
  • Do not play until a healthcare professional allows it

These are a few steps to follow, in sequential order, when recovering from a concussion:

  • Light aerobic exercise, no weightlifting
  • Moderate exercise, weightlifting allowed again
  • Heavy, noncontact exercise
  • Practice and controlled full-contact exercise
  • Competition

7 Risk and Complications

There are several risk factors and complications associated with chronic traumatic encephalopathy.

CTE occurs only in brains repeatedly injured by trauma. However, other factors may also contribute to the development of CTE, because not everyone with repetitive brain injuries will have cognitive, emotional, or behavioral problems later in life.

Factors contributing to CTE include:

  • Type, frequency, and severity of injuries, or any other medical factors
  • Tau protein, along with other proteins
  • Presence of apolipoprotein E (APOE) genotypes
  • Alzheimer's disease
  • Age
  • Sex
  • Stress
  • Alcohol or substance abuse


Several research initiatives are trying to gain further insight into the patterns of injury and changes in the brain associated with CTE. They are developing new strategies to diagnose, prevent, and treat CTE. To date, the Alzheimer’s Association has invested more than $2 million in this research. However, since there is no accurate marker for individuals with CTE, it is not possible to examine the incidence and prevalence of CTE, characterize its physiological changes, determine its genetic factors, or conduct diagnosis, treatment, or prevention. There has been research on potential biomarkers for diagnosis of CTE in living individuals. A PET radiotracer or ligand that specifically binds to tau in the brain is the most accurate biomarker of tau accumulation. Using this ligand, it is now possible to investigate tau pathology in living individuals. However, to investigate other brain-imaging markers, magnetic resonance diffusion measures as well as magnetic resonance spectroscopy measures may also be used to correlate them with PET tau findings, which will help develop safe and cost-effective CTE biomarkers.

8 Related Clinical Trials