It’s football season again, a time for tailgating, touchdowns, and traumatic brain injuries. Only a few weeks into the National Football League’s season, there have already been 14 concussions. (Frontline is tracking the season’s concussions, and breaking them down by position, team, and player.)

To make matters worse, new research on the brains of deceased former football players found high rates of chronic traumatic encephalopathy (CTE)—a degenerative disease believed to stem from repetitive brain injury.

Frontline reported on numbers from the Department of Veterans Affairs and Boston University, where researchers studied the brains of 165 people who played football at the high school, college, or professional level. They found evidence of CTE in 131 of them—79 percent. Of the brains studied, 91 of them belonged to former NFL players, and 87 of those 91 (96 percent) had signs of CTE.

Even with the caveat that the people likely to donate their brains to be posthumously examined for CTE also probably had reason to suspect that they had the disease, these numbers are overwhelming.

In the NFL’s 2015 Health and Safety Report, the league reported that concussions in regular season games have gone down by 35 percent since 2012, perhaps partially thanks to the league’s 2013 ban on players tackling with a blow from the crown of the head. In an attempt to further reduce concussions some teams are considering adopting a tackling style similar to that of rugby, where players tackle each other lower, grabbing the other’s legs, and hitting with their shoulders.