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.
One form of this cumulative damage has been recognized for a long time, called dementia pugilistica. The name comes from the observation that many boxers, also called pugilists, acquired a characteristic dementia by the end of their career. This was called being "punch-drunk". However, other people have neurodegenerative diseases caused at least in part by repetitive head injuries, particularly athletes in contact sports and military personnel.
What Kind of Head Injury Can Lead 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. PCS usually comes on very shortly after a head injury, but CTE occurs years later.
Besides Head Injury, What Other Risks Are There 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 it is associated with 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 is 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.
How is CTE Diagnosed?
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:
- memory impairment
- diminished ability to make decisions
- poor judgment
- poor impulse control.
- depression and suicide
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 known as chronic traumatic encephalomyelopathy (CTEM) which clinically mimicks Lou Gehrig’s disease (ALS), with muscle weakness and wasting, difficulty swallowing, and hyperactive reflexes.
Later on, 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 45-65. Behavioral variant frontotemporal dementia tends to progress more quickly than CTE, and often has a genetic component that CTE does not.
What Parts of the Brain Are Most Affected by CTE?
Often, there are changes in the
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.
What Tests Can Help Diagnose 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.
How Can CTE be Treated?
There is no treatment available for CTE once it has developed. As is usually the case, prevention is the best medicine. 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 is 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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Saulle M, Greenwald BD. Chronic traumatic encephalopathy: a review. Rehabil Res Pract. 2012;2012:816069. Epub 2012 Apr 10.
Shively S, Scher AI, Perl DP, Diaz-Arrastia R. Dementia Resulting From Traumatic Brain Injury: What Is the Pathology? Arch Neurol. 2012 Jul 9:1-7. (epub ahead of print)