"According to a statement from BU, Hernandez's brain was examined by Dr. Ann McKee, director of the CTE Center. The neurodegenerative brain disease has Alzheimer's-like symptoms, including memory loss, confusion, aggression, rage and, at times, suicidal behavior.
It is believed to result from repeated trauma to the head, which results in a buildup of the abnormal protein tau that clumps in the brain.
The disease is categorized in four degrees, with Stage 4 being the most severe. According to McKee's analysis, Hernandez was found to have Stage 3 CTE, which is commonly associated with cognitive and memory loss, as well as behavioral changes and impaired judgment. Hernandez was found to have early degeneration of brain cells and large tears in the septum pellucidum, a central membrane of the brain."
No wonder he was killing other people and himself in the end.