The Current Status of Research on Chronic Traumatic Encephalopathy.

Chronic traumatic encephalopathy (CTE) evolved from the term dementia pugilistica describing the dementia found in many boxers to its current use in describing the dementia and depression sometimes found in athletes subjected to multiple concussions or subconcussive blows to the head. Concurrently, the neuropathology evolved to specify a unique type of tauopathy found in perivascular spaces at the depth of sulci and other features not typically seen in neurodegenerative tauopathies. Four stages of CTE have been proposed, with 4 corresponding clinical syndromes of traumatic encephalopathy syndrome. However, it remains unclear whether this is a syndrome unique to repetitive head trauma, especially in contact sports, because the epidemiology has been difficult to establish. In particular, research to date has had a denominator problem in not establishing the total number of potential cases at risk for developing CTE. The current review examines the evidence to date for these syndromes and contributing or complicating factors affecting the neuropathology, neuroimaging, and clinical presentations associated with them.