Researchers studying the link between football and chronic traumatic encephalopathy found that 99 percent of the brains donated by families of former NFL players showed signs of the neurodegenerative disease, according to a new study published Tuesday.

In all, researchers from Boston University School of Medicine and the VA Boston Healthcare System examined 202 brains that belonged to men who played football at all levels and were later donated for research. They found CTE in 177 of them - 87 percent.

While they found evidence of the disease across all levels of play, the highest percentage was found among those who competed at the highest level; all but one of the 111 brains belonging to ex-NFL players were diagnosed post-mortem with CTE.