Chronic traumatic encephalopathy: clinical presentation and in vivo diagnosis.

Exposure to repetitive head impacts from contact sport participation (e.g., American football, boxing, soccer) is associated with the neurodegenerative disorder known as chronic traumatic encephalopathy (CTE). The neuropathology of CTE is becoming well defined, and diagnostic criteria have been developed and are being refined. The critical next step in this emerging field is the diagnosis of CTE during life. The objective of this chapter is to describe what is currently known about the clinical presentation and in vivo diagnosis of CTE. This chapter reviews studies in which clinical manifestation of CTE was examined through retrospective telephone interviews with informants of individuals whose brains were donated and were diagnosed with CTE through neuropathologic examination. In vivo research examining the long-term neurobehavioral consequences of repetitive head impacts is also reviewed, followed by a comparison of the existing provisional clinical diagnostic criteria for CTE, as well as preliminary research on possible fluid and neuroimaging biomarkers. An illustrative case study of CTE is presented, and the chapter concludes with a discussion of gaps in knowledge and future directions.