Chronic Traumatic Encephalopathy (CTE) is a progressive degenerative disease of the brain found in athletes (and others) with a history of repetitive brain trauma. This trauma, which includes multiple concussions, triggers progressive degeneration of the brain tissue, including the build-up of an abnormal protein called tau. These changes in the brain can begin months, years, or even decades after the last concussion or end of active athletic involvement. The brain degeneration is associated with memory loss, confusion, impaired judgment, paranoia, impulse control problems, aggression, depression, and, eventually, progressive dementia.

CTE can only be definitively diagnosed through post-mortem examination of the brain, although efforts are underway to learn how to diagnose CTE in living people, a key step to developing a treatment for the disease.

First called “punch drunk”  syndrome and dementia pugilistica, CTE was first described in 1928 by New Jersey pathologist  Harrison Martland in “Martland HS: Punch drunk. JAMA 91:1103–1107, 1928” in which he noted symptoms such as slowed movement, tremors, confusion, and speech problems typical of the condition. In 1973, a group led by J.A. Corsellis described the typical neuropathological findings of CTE after post-mortem examinations of the brains of 15 former boxers.

The term “Chronic Traumatic Encephalopathy” appears in the medical literature as early as 1966 and is now the preferred term. Through 2009 there were only 49 cases described in all medical literature since 1928, 39 of whom were boxers. Many thought this was a disease exclusive to boxers, although cases have been identified in a battered wife, an epileptic, two mentally challenged individuals with head-banging behavior, and an Australian circus performer who was also involved in what the medical report authors referred to as “dwarf-throwing.”