Chronic traumatic encephalopathy (CTE) is a progressive degenerative brain disease that is caused by repetitive head injuries or concussions. Symptoms of CTE may include mood and behavioral changes, memory loss, difficulty with thinking and problem-solving, and motor problems. CTE can only be definitively diagnosed after death through post-mortem examination of the brain. While there is no cure for CTE, treatment may focus on managing symptoms and improving quality of life. Preventative measures such as avoiding head injuries and treating concussions promptly may reduce the risk of developing CTE.

Repetitive head trauma is likely the cause of CTE. Football and ice hockey players, as well as military personnel serving in war zones, have been the focus of most CTE studies, though other sports and factors such as physical abuse also can lead to repetitive head injuries.

However, not all athletes and not everyone who experiences repeated concussions, including military personnel, go on to develop CTE. Some studies have shown no increased incidence of CTE in people exposed to repeated head injuries.

In brains with CTE, researchers have found that there is a buildup of a protein called tau around the blood vessels. Tau buildup in CTE is different from accumulations of tau found in Alzheimer's disease and other forms of dementia. CTE is thought to cause areas of the brain to waste away (atrophy). Injuries to the sections of nerve cells that conduct electrical impulses affect communication between cells.

It's possible that people with CTE may show signs of another neurodegenerative disease, including Alzheimer's disease, amyotrophic lateral sclerosis (ALS) — also known as Lou Gehrig's disease — Parkinson's disease or frontotemporal lobar degeneration (frontotemporal dementia).

There is no treatment for CTE. But CTE may be prevented because it is associated with recurrent concussions. Individuals who have had one concussion are more likely to have another head injury. The current recommendation to prevent CTE is to reduce mild traumatic brain injuries and prevent additional injury after a concussion.

CTE is a progressive, degenerative brain disease for which there is no treatment. More research on treatments is needed, but the current approach is to prevent head injury. It's also important to stay informed about the latest recommendations for detecting and managing traumatic brain injury.