A new study paints an alarming portrait of the dangers of concussions in the NFL.

A report by PBS' Frontline on Friday revealed that 96 percent of deceased NFL players tested positive for chronic traumatic encephalopathy (CTE), a degenerative disease believed to result from repetitive trauma to the head.

The study, conducted by researchers with the Department of Veterans Affairs and Boston University, showed that 87 of 91 pro football players who donated their brains for testing were found to have CTE. Symptoms of the disease include memory loss, depression and dementia.

More from FoxSports

"People think that we're blowing this out of proportion, that this is a very rare disease and that we're sensationalizing it," said Ann McKee, the director of the brain bank, a collaboration between the VA and BU. "My response is that where I sit, this is a very real disease. We have no problem in identifying it in hundreds of players."

CTE has been identified in the brains of Junior Seau and Dave Duerson, who each committed suicide, as well as Hall of Fame center Mike Webster, the first former NFL player to be linked to the disease. In fact, the upcoming movie "Concussion" focuses on the neurosurgeon (Bennet Omalu) who initially examined Webster's brain in 2013 and identified the signs of CTE.

The NFL, which helped fund research to the brain bank with a $1 million grant in 2010, reported in its 2015 Health and Safety Report that concussions had dropped 35 percent (from 173 to 112) in a three-year span from 2012-14). Frontline's report, citing information provided by the teams in the preseason and playoffs, put that number at 28 percent.

"We are dedicated to making football safer and continue to take steps to protect players, including rule changes, advanced sideline technology, and expanded medical resources," an NFL spokesman said in response to the report.

The study was not exclusive to the NFL. It examined 165 football players who competed at levels ranging from professional to high school and found that 131 were afflicted with CTE.

(h/t PBS.org)