Chronic traumatic encephalopathy
DEFINITION
Chronic traumatic encephalopathy (CTE) results from blows to the head over a period of time that cause concussion (mild traumatic brain injury). These injuries lead to difficulties with thinking (cognition), emotions and behaviors that do not become noticeable until many years later. CTE can lead to physical problems as well. Not everyone who has one or more concussions develops CTE.
CTE involves progressive damage to nerve cells (neurodegenerative disease). The damage results in visible changes to the brain. Some of these changes can be seen with brain imaging, but a diagnosis at this time can be made only on inspection after death (autopsy). Researchers are working to find a way to diagnose CTE in those who have the disease while the individuals are still alive.
Originally called punch drunk syndrome (dementia pugilistica), CTE was first demonstrated in boxers. Doctors now know that other individuals who play a wide variety of sports that involve repeated blows to the head, such as football players, can develop CTE. Military personnel who have had blast injuries also are at risk.
Researchers do not yet fully understand CTE’s prevalence and causes. There is no cure for CTE.
CAUSES
Initial injury
The main cause of CTE is repetitive head trauma. Football players have been the focus of most CTE studies. However, athletes participating in other sports, including soccer, ice hockey, rugby, boxing, wrestling, basketball, field hockey, cheerleading, volleyball and lacrosse, may experience repeated head impacts and also have high rates of concussion.
Blast injuries to military personnel also can result in CTE.
However, not all athletes and not everyone who experiences repeated concussions, including military personnel, go on to develop CTE.
Effect of injury
CTE causes the wasting away (atrophy) of many parts of the brain. Injuries to the section of nerve cells involved in conducting electrical impulses (axons) interfere with cell-to-cell communication. Other changes include deposits of the proteins tau and TDP-43, and changes in white matter — the part of the brain made up of nerve fibers. Unlike in Alzheimer’s disease, deposits of beta-amyloid, another protein, are not common.
More than one-third of people with CTE also have signs of another neurodegenerative disease, including Alzheimer’s disease, motor neuron disease, Parkinson’s disease or frontotemporal lobar degeneration.
SYMPTOMS
Symptoms of CTE are like those of other conditions that involve progressive loss of function or structure of nerve cells (neurodegenerative diseases), including:
- Alzheimer’s disease
- Parkinson’s disease
- Frontotemporal dementia
- Amyotrophic lateral sclerosis (ALS) — also known as Lou Gehrig’s disease
Overall, people with CTE first have problems with thinking (cognition), mood and behavior. Later, they may also develop physical problems.
Military personnel who have experienced traumatic brain injury may experience post-traumatic stress disorder.
Signs and symptoms of CTE usually begin eight to 10 years after repetitive mild traumatic brain injury. These include:
- Difficulty thinking (cognitive impairment)
- Impulsive behavior
- Depression or apathy
- Short-term memory loss
- Difficulty planning and carrying out tasks (executive function)
- Emotional instability
- Substance abuse
- Suicidal thoughts or behavior
Over time, memory and executive function may become worse, and other signs and symptoms may develop, including:
- Irritability
- Aggression
- Speech and language difficulties
- Motor impairment, such as difficulty walking, tremor, loss of muscle movement, weakness or rigidity
- Trouble swallowing (dysphagia)
- Vision and focusing problems
- Trouble with sense of smell (olfactory abnormalities)
- Dementia
Researchers use the following stages to describe the progression of CTE symptoms:
- Stage I. Headache, loss of attention and concentration
- Stage II. Depression, explosivity and short-term memory loss
- Stage III. Decision-making (executive) dysfunction and cognitive impairment
- Stage IV. Dementia, word-finding difficulty and aggression
They have also created four stages to describe the process of damage to brain tissue.
- CTE causes ongoing pathological changes that once are started, continue to have an effect for years or decades after the original traumatic brain injury or after an individual retires from a sport. Symptoms progress throughout an individual’s life.
- CTE progresses in two patterns. In younger people, it may begin with behavior and mood changes, whereas in older people, it may begin with cognitive problems that progress and may lead to dementia. It’s not known whether there are two different disease processes or if the process changes over time.
When to see a doctor
CTE develops over many years, long after repeated mild traumatic brain injury occurs.
However, see your doctor in case of the following:
- Suicidal thoughts. Some studies report that people with CTE may be at increased risk of suicide. If you have thoughts of hurting yourself, call 911, your local emergency number or the National Suicide Prevention Lifeline at 800-273-TALK (800-273-8255).
- Head injury. See your doctor if you have had a head injury, even if you didn’t need emergency care. If your child has received a head injury that concerns you, call your child’s doctor immediately. Depending on the signs and symptoms, your doctor may recommend seeking immediate medical care.
- Memory problems. See your doctor if you have concerns about your memory or other thinking (cognitive) or behavior problems.
- Personality or mood changes. See your doctor if depression, anxiety, aggression or impulsivity occur.
