Chronic traumatic encephalopathy (CTE) is a degenerative brain disorder that is caused by repeated head injuries and blows to the head. It is a progressive and fatal brain disease that causes the death of nerve cells in the brain, known as degeneration. CTE gets worse over time and leads to dementia. The only way to definitively diagnose CTE is after death during an autopsy of the brain. 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 Alzheimers disease and other forms of dementia. Symptoms of CTE are thought to include trouble with thinking and emotions, physical problems, and other behaviors. Its thought that these develop years to decades after head trauma occurs. There is no cure or treatment for CTE, but certain medicines may be used to temporarily treat the cognitive (memory and thinking) and behavioral symptoms. Preventing head injuries is the best way to address this permanent condition.