Chronic traumatic encephalopathy (CTE) is a progressive brain condition linked to repeated head injuries, particularly common among athletes in contact sports like boxing or football. CTE is characterized by the gradual deterioration of brain regions responsible for memory, cognition, behavior, personality, and motor skills. Symptoms may start years or even decades after the last head injury, leading to various cognitive, emotional, and physical challenges.
Understanding the Causes of CTE
The exact mechanism behind CTE development remains unclear. Researchers have identified the abnormal buildup of tau protein in affected brain cells as a hallmark of the condition. Normally present in the brain, tau accumulates to toxic levels in CTE, causing nerve cells to lose function and die, which ultimately leads to brain shrinkage. This tau pathology progresses over time, impairing cognitive function, mood regulation, and motor abilities.
Repeated head trauma, such as traumatic brain injury (TBI) or concussions, is a known risk factor for CTE. However, it's uncertain if a single injury can lead to CTE, and not all individuals who sustain concussions develop the condition. Age may influence CTE progression, with symptoms often appearing years after the last injury or the end of an active sports career.
Symptoms and Progression of CTE
CTE may manifest in different ways in different people. People with CTE may have trouble remembering things and concentrating. They may have changes in their behavior and personality, including violent outbursts, increased frustration, mood swings, and lack of interest in people and things they previously cared about. Thinking and behavior changes in CTE usually begin very mildly, and the person and their family may not notice significant changes at first.
Early symptoms may include mild memory loss, headaches, irritable mood, slurred speech, or unsteadiness when walking. People with CTE may have trouble concentrating, organizing or planning tasks, remembering answers to questions they ask or doing more than one task at a time. Later in the disease, memory, mood, behavior, and problems with speech. People with CTE may become depressed or anxious and may act more aggressively and inappropriately in social situations. They may get lost. Speech may also get worse, and people with CTE may become harder and harder to understand. Worsening problems with walking and balance may increase the risk for falls late in the disease. A person with CTE can live many years with the disease.
New Diagnostic Criteria for Traumatic Encephalopathy Syndrome (TES)
To improve CTE research, an expert consensus panel has developed research diagnostic criteria for Traumatic Encephalopathy Syndrome (TES), a clinical disorder associated with neuropathologically confirmed CTE. TES diagnosis involves a four-step process:
- Documenting substantial exposure to repetitive head impacts (RHI).
- Identifying core clinical features, such as cognitive impairment (in episodic memory or executive function) or neurobehavioral issues.
- Ruling out other neurological, psychiatric, or medical conditions that could explain these symptoms.
- Assessing the level of functional dependence, graded on a five-point scale from independent to severe dementia.
For research purposes, the panel introduced provisional levels of CTE diagnostic certainty based on RHI exposure, core clinical symptoms, functional status, and other supportive signs like delayed onset, motor abnormalities, and psychiatric symptoms. These levels range from suggestive to definite but are not intended for clinical diagnosis or patient communication.
Future Directions
TES diagnostic criteria currently rely heavily on clinical observations and lack validated biomarkers for CTE. Further research aims to establish objective measures of CTE pathology, investigating the relationship between tau accumulation, clinical symptoms, and other possible contributing factors, such as white matter changes and inflammation.
Are There Medicines to Treat CTE?
There is no cure for CTE, but some medications can help manage mood and behavioral symptoms. Treatments commonly used in Alzheimer's disease may offer some cognitive support for those with CTE. Research and clinical trials are ongoing to explore potential treatments targeting tau protein and other pathways implicated in CTE.
