Chronic Traumatic Encephalopathy Fast Facts

Chronic traumatic encephalopathy (CTE) is a degenerative brain disease that can only be diagnosed during an autopsy after the sufferer’s death.

CTE is connected to a history of repeated head trauma, although researchers don’t yet know precisely what causes the condition.

One study found CTE in the brains of 99% of the National Football League players that researchers have studied. The study also noted that CTE was found in 91% of college football players and 21% of high school football players whose brains had been examined for the condition. Other studies have found similar rates in American football players.

United Brain Association

Chronic traumatic encephalopathy (CTE) is a degenerative brain disease that can only be diagnosed during an autopsy after the death of the sufferer.

What is Chronic Traumatic Encephalopathy?

Chronic traumatic encephalopathy (CTE) is a degenerative brain disease that seems to be caused by repeated head trauma. CTE is especially poorly understood among brain diseases because it cannot be definitively diagnosed in a living patient. The condition can only be diagnosed when the patient’s brain tissue is examined during an autopsy after death.

Because researchers can’t get a clear look at CTE in living patients, it’s very difficult to determine the disease’s causes, symptoms, or prognosis. CTE seems to be linked to repeated head traumas and probably takes years to develop. It doesn’t seem to be caused by a single incident of head trauma. However, it is not clear how many head traumas put a patient at risk of developing CTE over a certain period of time.

CTE is rare, but athletes who regularly experience head traumas (football players, hockey players, boxers, wrestlers, etc.) seem to be especially at risk. Even this is difficult to confirm, though, because athletes’ brains are usually only examined for CTE when they’ve experienced CTE signs while they were alive. This could make the rate of CTE in athletes appear to be much higher than it is.

Possible Symptoms of CTE

The uncertainty surrounding CTE also makes it hard to say for sure what symptoms it causes. The disease seems to cause problems with thinking, mood, emotions, and behavior. Suspected symptoms of CTE include:

  • Depression, anxiety, or loss of interest in daily activities
  • Difficulty with thinking, planning, organization, or problem-solving
  • Short-term memory loss
  • Impulsive behavior
  • Unstable emotional state
  • Aggression
  • Substance abuse
  • Suicidal thinking, suicide attempts, or successful suicide

What Causes Chronic Traumatic Encephalopathy?

The actual cause of CTE is unknown. Repeated head injuries very likely cause the disease over an extended time. It’s not known what type of injuries leads to the development of the disease.  CTE may result from repeated concussions or traumatic brain injuries.  Multiple minor blows to the head that don’t show any symptoms at the time may also cause CTE.

Scientists believe that recurring head injuries cause the buildup of a protein in the brain that, over time, causes brain cells to die. As more and more cells die, the patient begins to experience the types of symptoms that seem to be characteristic of CTE.

Is Chronic Traumatic Encephalopathy Hereditary?

As with every other aspect of the disease, it remains a mystery whether CTE risk can be inherited. There hasn’t yet been a study that shows a definitive connection between CTE and inherited risk factors.

However, one recent study has detected a possible connection between genetics and the severity of CTE symptoms in people who suffer from the disease. Researchers at Boston University School of Medicine and the VA Boston Healthcare System identified a particular gene variation associated with severe CTE symptoms.

The scientists looked at pro-and anti-inflammatory cytokines and those that affect repair and plasticity (e.g., neurotrophic genes) and found that variations in these genes were more common in CTE sufferers with more pronounced symptoms. The gene variation, however, was no more common in CTE sufferers than in patients without CTE. That suggests that the gene isn’t necessarily the cause of CTE, but it may increase the likelihood of worsening symptoms.

The research is preliminary, and the study’s authors don’t suggest that they’ve found a genetic cause for CTE. The study is one of the first, though, to find a connection between a gene and CTE, and it could provide the basis for further research.

How is Chronic Traumatic Encephalopathy Detected?

Understandably, there’s very little reliable data about how to spot the earliest signs of CTE or even the certainty that it is possible to spot the disease in its early stages at all. It’s possible to be alert for the suspected symptoms of CTE, such as abnormal mood, behavior, or cognitive symptoms. Still, many of those symptoms could also be signs of other physical or mental illnesses.

In the absence of solid knowledge about CTE, some scientists are trying to develop ways to identify suspected CTE by looking for its symptoms. Researchers at the University of Michigan have created diagnostic criteria for a condition they call traumatic encephalopathy syndrome (TES).

TES is defined by symptoms–mood and behavior changes, physical motor problems, etc.–that are also associated with CTE. TES can be suspected when a patient has a history of repeated head injuries and other possible causes of the symptoms have been ruled out. The goal is to use the diagnosis to spur doctors to pursue treatments that might slow CTE progression.

How is Chronic Traumatic Encephalopathy Diagnosed?

There are currently no exams or tests that can detect CTE. The key to diagnosing the disease is identifying the abnormal buildup of specific proteins in the brain. No current imaging or lab tests are available to find the protein clusters. Researchers are actively trying to develop diagnostic tools, but until they do, CTE can only be diagnosed by directly examining brain tissue after death.


How is Chronic Traumatic Encephalopathy Treated?

CTE seems to be degenerative, meaning it gets worse over time, and the damage it causes is irreversible, at least by any means currently known. Therefore, there’s no known treatment, even if it were possible to diagnose the disease in a living patient. When CTE is suspected, the current treatment protocol is to protect the patient from further head injuries.

How Does Chronic Traumatic Encephalopathy Progress?

A 2012 study by researchers at Boston University identified four CTE stages based on the increasing severity of abnormal protein buildup in patients’ brains. Progressively severe symptoms characterize the four stages.

  • Stage I. Symptoms of this stage include headaches and problems with attention and concentration.
  • Stage II. The second stage’s symptoms include those of the first stage, as well as short-term memory loss, depression, and explosive moods.
  • Stage III. Symptoms of this stage include problems with organization, planning, multitasking, and other cognitive difficulties.
  • Stage IV. In stage IV, memory problems become more severe. Often, dementia follows. Cognitive and mood issues also become more severe, and aggression may become pronounced. Suicidal behavior is also common in this stage.

How is Chronic Traumatic Encephalopathy Prevented?

The only sure way to prevent CTE is to avoid head injuries entirely. No one knows the threshold for developing the disease, so it’s impossible to say for sure how many head injuries over what time span is too many.

Steps you can take to reduce your risk include:

  • Avoid contact sports or other situations that come with a risk of head injuries.
  • If you participate in risky activities, always use proper protective gear and consistently follow safety rules and guidelines.
  • If you receive a head injury, treat it correctly according to the advice of medical professionals. Take precautions to avoid future head injuries after the first.

Chronic Traumatic Encephalopathy Caregiver Tips

If your loved one is suffering from symptoms consistent with CTE, you can help them function more effectively. You can also take steps to help yourself cope with the disease’s consequences, which become harder to deal with over time.

  • Learn all you can about the disease and its effects. Knowing what to expect as the disease progresses can help you to cope as symptoms worsen.
  • Help your loved one to establish routines. The memory and cognitive problems that come with CTE can be managed more effectively if your loved one has a system of reliable routines and memory aids. A comforting routine may also make mood swings and behavior fluctuations easier to deal with.
  • Be aware of the dangers. Both aggressive and suicidal behaviors are thought to be symptoms of advanced CTE. Be alert to the development of these symptoms, and take steps to keep your loved one and yourself safe.
  • Get help for yourself. As is the case with all degenerative brain diseases, CTE takes its toll on caregivers, too. Don’t be afraid to step away from the situation when you feel overwhelmed, and look for a support system, either locally or online, from other caregivers and loved ones dealing with the disease.

CTE is often associated with other brain and mental health-related issues, a condition called co-morbidity. Here are a few of the disorders commonly associated with CTE:

Chronic Traumatic Encephalopathy Brain Science

CTE is characterized by the buildup of a protein in the brain called tau. Tau protein clusters, also found in the brains of people with Alzheimer’s disease, are thought to play a role in the progressive death of brain cells. The loss of these cells produces the symptoms associated with CTE, and as more cells die, the symptoms worsen.

Unfortunately, there is currently no way to detect small tau protein clusters in living patients’ brains, a limitation that makes it impossible to diagnose CTE before death. The inability to diagnose the disease while it’s active stands in the way of learning more about CTE. One active area of CTE research is focused on developing diagnostic tools that can detect tau proteins and, potentially, identify the disease in living patients.

  • Imaging markers. Researchers are trying to find chemical markers that will bind with tau proteins. These markers could then be detected by imaging technologies such as positron emission tomography (PET) scans.
  • New lab tests. Researchers have recently developed a test that can detect tau protein filaments quickly and with great sensitivity. The test was initially developed to diagnose Creutzfeldt-Jakob disease, another degenerative brain condition.  Over the past decade, the test’s sensitivity has been improved to look for diseases such as Parkinson’s. New advances in the test may make it sensitive enough to spot signs of Alzheimer’s and CTE. The test may also aid research into methods for preventing the development of tau protein clusters in the first place.

Chronic Traumatic Encephalopathy Research

Title: The DIAGNOSE-CTE Research Project (DIAGNOSE-CTE)

Stage: Recruiting

Principal investigator: Robert A Stern, PhD 

Boston University School of Medicine

Boston, MA

Chronic Traumatic Encephalopathy (CTE) is a neurodegenerative disease characterized by a distinct deposition of phosphorylated tau (p-tau) in neurons and astrocytes in a pattern that is unique from other tauopathies, including Alzheimer’s disease (AD). Although the neuropathological features of CTE have become further clarified in recent years, the clinical presentation of CTE is still not well characterized. Diagnostic criteria have only recently been published and lack validation.

Neuroimaging and fluid biomarkers developed to diagnose other neurodegenerative diseases have only been used in preliminary studies of individuals at high risk for CTE, namely athletes with histories of significant exposure to repetitive head impacts (RHI), such as former football players and boxers. Thus, there is an urgent need to develop accurate methods for detecting and diagnosing CTE during life to develop effective interventions for prevention and treatment. Moreover, though a history of RHI is a necessary risk factor for CTE, it alone is not sufficient. There is a need to understand what specific aspects of RHI exposure place an individual at increased risk for CTE and examine potential genetic polymorphisms that modify that risk.

To address these needs, the investigators are conducting a multidisciplinary, multicenter, longitudinal study of former NFL and varsity college football players (with and without symptoms) and a control group of asymptomatic same-age men without any history of RHI exposure, traumatic brain injury, or military service. Subjects will be seen at 1 of 4 participating study sites in Boston, Las Vegas, New York, and Scottsdale/Phoenix. Subjects will undergo a baseline evaluation and a 3-year follow-up evaluation (currently, former college players will not complete the follow-up evaluation). Each assessment will take place over 3 days and consist of the following procedures/tests: neurocognitive testing, determination of functional independence, neuropsychiatric examination (with measures of mood and behavior), neurological assessment (motor, headache, postural stability), neuroimaging (including structural, diffusion, functional, biochemical, and molecular imaging), lumbar punctures (for Cerebrospinal Fluid (CSF) biomarkers), blood draws (for blood biomarkers and DNA), and saliva samples (for biomarkers).


Title: Contributions of mTBI to Neurodegeneration Due to CTE and Alzheimer’s Disease

Stage: Not Yet Recruiting

Principal investigator: Katherin Turk, MD 

VA Boston Healthcare System

Jamaica Plain, MA

The specific aim of this project is to examine whether veterans with mild Traumatic Brain Injuries are at risk for dementia by studying their memory, brain wave activity, brain structure, and proteins that can be elevated after brain injury and in dementia.

This study will recruit patients with a history of mild-moderate traumatic brain injury, mild cognitive impairment, as well as healthy controls to better understand how single or repetitive mild Traumatic brain injuries may contribute to the development of dementia. It will be prospective in nature. Participants will be asked to complete a series of 3 study sessions. During the first study session, each subject will be asked to complete a neuropsychological assessment. If the subject’s testing scores fall under the study criteria, they will also be asked to complete a computer task. In the second study session, the subject’s brain waves will be analyzed using an EEG while completing a computer task. During the computer task, the subjects will be asked to study a list of words, and we will test the subjects on their memory for those words. During the final study session, we will ask subjects to complete: (1) an MRI, (2) a standard blood draw procedure, and (3) a lumbar puncture procedure.

Clinical Implications: These studies will provide a better understanding of which individuals with Traumatic Brain Injury will develop dementia, and how many years in the future dementia may occur.


Title: Alzheimer’s Autism and Cognitive Impairment Stem Cell Treatment Study (ACIST)

Stage: Recruiting

Study Director: Steven Levy, MD 

MD Stem Cells

Westport, CT

Cognition is the process of generating thoughts, recalling memories, processing information, and higher-order associations, including social interactivity that all take place in the brain. It requires sufficient health and interactivity of neurons in the brain, including their ability to form and maintain synaptic connections.

Cognitive impairment results from the loss of these abilities. ACIST will test the hypothesis that the delivery of Bone Marrow-Derived Stem Cells (BMSC) via the methods in the study with or without the addition of Near Infrared Light will improve cognition through the ability of BMSC to positively affect the health and function of neurons and the brain.

Patients enrolling with cognitive impairment will require assessment with the Mini-Mental Status Exam (MMSE). A score of 24 or less will be required. Progressive dementias such as Alzheimer’s Disease (ALZ) show a decline of 2 to 4 points per year on MMSE. The goal for ACIST in progressive and stable dementia will be a patient’s stability over the 1-year follow-up and ideally an improvement of 3 points on MMSE.

Patients enrolling with Autism Spectrum Disorder (ASD) will be required to be adults (over 18 years of age) and to have a score on the Autism Spectrum Quotient of 20 or above. The goal will be a decrease of 5 or more on the scale over the 1-year follow-up period.

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