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:
- 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)
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.