What to Know Serious illnesses have been linked to concussions, including Alzheimer's disease, Parkinson's disease.

The NFL has acknowledged there is a link between football and chronic traumatic encephalopathy, or CTE.

Chargers great Junior Seau was found to have suffered from CTE, a disease where protein forms clumps in the brain.

California is limiting full-contact practices for youth football teams to reduce brain injuries.

Gov. Gavin Newsom signed a law Wednesday limiting full-contact practices to 30 minutes per day, twice a week. The practices are banned entirely during the offseason.

Previous state law had limited full-contact practices for middle and high school football teams to 90 minutes per day, twice per week.

The new law also requires a medical professional to be present for all games and an independent person to attend all practices. They will have the authority to remove players who show signs of an injury.

The state legislature approved the bill earlier this month with no opposition.