Rates of disease have been found to be about 30% among those with a history of multiple head injuries. Population rates, however, are unclear. Professional level athletes are the largest group with<unk> , due to frequent concussions and sub-concussive impacts from play in contact sport. These contact-sports include American football, Australian rules football, ice hockey, Rugby football (Rugby union and Rugby league), boxing, kickboxing, mixed martial arts, association football, and wrestling. In association football, only prolific headers are known to have developed<unk> . Cases of<unk>  were also recorded in baseball. According to a 2017 study on brains of deceased gridiron football players, 99% of tested brains of NFL players, 88% of CFL players, 64% of semi-professional players, 91% of college football players, and 21% of high school football players had various stages of<unk> . Other individuals diagnosed with<unk>  were those involved in military service, had a previous history of<unk>  seizures, were domestically abused, or were involved in activities resulting in repetitive head collisions.
Chronic traumatic encephalopathy
Parkinson's disease
Wernicke encephalopathy
Alzheimer's disease
Powassan encephalitis
Posterior reversible encephalopathy syndrome
Toxic encephalopathy
Viral encephalitis