What Is Chronic Traumatic Encephalopathy?

Symptoms, Risk Factors, and Diagnosis of CTE


There is a growing awareness among physicians that the problems acquired after a head injury do not always quickly resolve. This is especially true of people who have multiple head injuries, particularly athletes in contact sports and military personnel.

Head Injuries Leading to CTE

No major head injury is needed. Mild traumatic brain injury (mTBI) or even less minor head injuries can contribute. After a concussion, some people suffer from a post-concussive syndrome (PCS) of nausea, headache, and confusion. But CTE is more than just a prolonged period of post-concussive syndrome—it occurs years later, unlike PCS, which usually comes on very shortly after a head injury.

Other Risks for CTE

Although CTE is very different from Alzheimer’s disease in many ways, they may share a genetic risk factor. ApoE4 is the most widely known genetic risk factor for late-onset Alzheimer’s. People with ApoE4 mutations also have been shown to have longer recovery times from head injury, and more severe deficits after a single head injury. However, other studies have suggested that there is no link between CTE and ApoE4. More research into this possible connection is needed.

Women seem to have more prolonged recovery from concussions than men, but it's not known if this leads to a different risk of developing CTE. Most of the brains studied with CTE have been male due to the majority being contact athletes or combative military personnel. The brain changes associated with CTE have been found even in very young people with multiple head traumas, but the changes worsen with age.


Officially chronic traumatic encephalopathy (CTE) can only be diagnosed by autopsy. Certain proteins, such as tau and TDP-43, accumulate in the brain. This is distinct from Alzheimer’s disease, which shows beta-amyloid plaques, which is present in less than half of cases with CTE. Furthermore, the initial changes are more common around blood vessels.

Despite the ultimate need for confirmation by autopsy, there are symptoms that are highly suggestive of CTE, including the following:

In addition, there are some physical signs of CTE that may be present, including:

  • difficulty with balance and walking
  • Slowed, slurred speech
  • Parkinsonism (tremor, rigidity, and slow movements)

There is also a small subset of patients with CTE who have chronic traumatic encephalomyelopathy (CTEM). This disorder mimics the symptoms of Lou Gehrig’s disease (ALS), with muscle weakness and wasting, difficulty swallowing, and hyperactive reflexes.

Later on in the course of CTE, the patients will suffer from dementia. Rather than Alzheimer’s disease, the symptoms of chronic traumatic encephalopathy more closely resemble the behavioral variant of frontotemporal dementia (bvFTD). However, CTE usually comes on a little earlier than bvFTD, between the ages of 30 to 50 rather than 45 to 65 years of age. Behavioral variant frontotemporal dementia tends to progress more quickly than CTE, and often has a genetic component that CTE does not.

Effects on the Brain

There is reduced brain weight and thinning of the corpus callosum, which connects the brain's two hemispheres.

There is also frequent atrophy of the frontal lobes in CTE. The frontal lobes control our ability to make good decisions and plan, as well as allowing us to retrieve memories.

Other affected areas of the brain include the mammillary bodies and hippocampus, which are involved with memory, as well as the substantia nigra, which is involved with movement.

Testing for CTE 

While public awareness of CTE has grown rapidly recently, science is typically slower to develop tests that are specific to the problem. An MRI can help rule out other diseases, and may show abnormal wasting of the amygdala, which could suggest CTE as a diagnosis. Other more experimental techniques such as functional MRI are also being explored.

CTE Treatment 

There is no treatment available for CTE once it has developed. As is usually the case, prevention is the best medicine.

Prevention Is Key 

The need for a safe culture in sports and the rest of life is becoming increasingly emphasized. Athletes need to be encouraged to report when they are suffering from effects of a head injury, and follow guidelines for returning to play after such an injury. It's also the role of coaches to teach their players correct techniques for personal protection. It’s good to play hard, but it’s even more important to play safe.

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Article Sources
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  • Saulle, M., & Greenwald, B.D. (2012). Chronic traumatic encephalopathy: a review. Rehabilitation Research and Practice, 816069. Epub 2012 Apr 10.
  • Shively, S., Scher, A.I., Perl, D.P., & Diaz-Arrastia, R. (2012). Dementia Resulting From Traumatic Brain Injury: What Is the Pathology? Archives of Neurology, Jul 9:1-7.