A Boston University study on the brains of 202 former football players from all different ages and skill levels found a shockingly high occurrence of chronic traumatic encephalopathy, or CTE, especially among NFL players.

The results of the study were published Tuesday in the Journal of the American Medical Association and showed that out of those 202 players, 177 of them showed signs of CTE. But on the professional level, it was much worse, as 110 of 111 donated brains from NFL players tested positive for the disease.

“To me, this says that this a public health problem, something that should concern parents and athletes,” Ann C. McKee, director of BU’s CTE Center and chief of neuropathology at the Boston VA, told The Boston Globe. “All the participants were exposed to a relatively similar type of repetitive head trauma while playing the same sport.”

The BU researchers expected the majority of subjects to have some form of CTE, McKee said, because the brains were donated by relatives who saw symptoms of the disease — which include agitation, thoughts of suicide, explosive anger and memory loss, among others — before their loved ones’ deaths, but even they were surprised by the results.

BU’s data can’t be used to measure causation or prevalence of the disease, but it does show a correlation between football and CTE.

UCLA Brain Injury Research Center director David A. Hovda also pointed out to the Globe that many of the subjects played before improvements were made to the rules and to football equipment, which means we don’t know how (or if) those factors have affected CTE’s impact. The study also didn’t include player positions or how aggressively they played, but Hovda called it an “excellent study,” nonetheless.

The NFL said in a statement that it plans to keep supporting further research into CTE.

“The medical and scientific communities will benefit from this publication, and the NFL will continue to work with a wide range of experts to improve the health of current and former NFL athletes,” the statement said, per the Globe. “The NFL is committed to supporting scientific research into CTE and advancing progress in the prevention and treatment of head injuries.”

Thumbnail photo via Kirby Lee/USA TODAY Sports Images