during autopsy, in individual who were subjected to repetitive brain trauma.
Other than professional athletes, CTE occurs inmilitary personnel who served in Iraq or Afghanistan and people who only played high school sports.
Individuals with epilepsy, or those with developmental issues that involve head banging and those who are victims of domestic abuse also were diagnosed with CTE.
The article indicates that this suggests that repetitive trauma is a needed condition.
http://pnl.bwh.harvard.edu/education/what-is/chronic-traumatic-encephalopathy/