In the first and second decade of the 21st century, the relationship between football, brain injuries, and chronic traumatic encephalopathy (CTE) began to be explored in earnest. Investigations showed that many brains of deceased football players have CTE, which causes speech and gait difficulties, cognitive dysfunction, problems with memory, and changes in behavior and personality.

Controversy arose when the NFL was accused of denying the concussion crisis and subsequent CTE diagnoses for NFL players.

Football is not the only sport that can cause CTE, for example, CTE is also common in boxers.

In 2015, there was a Sport Concussion Summit to discuss this issue. This website archived the social media presence surrounding the speakers and events. Explore here:

According to the 2015 American Heritage Dictionary of Medicine, chronic traumatic encephalopathy (also referred to as dementia pugilistica) is defined as "a neurodegenerative disease resulting from repetitive trauma to the brain, characterized by speech and gait difficulties, cognitive dysfunction, memory disturbances, and changes in behavior and personality."

Chronic Traumatic Encephalopathy can occur from sports like boxing and football.