Examination of the brains of four former Canadian Football League players revealed two suffered from a brain disease, researchers say. Dr. Lili-Naz Hazrati, a neuropathologist in the Laboratory Medicine Program at the University Health Network, says of the four brains donated to the Canadian Sports Concussion Project, two of the former football players suffered from the brain disease Chronic Traumatic Encephalopathy, while two did not. Bobby Kuntz, a former Toronto Argonaut and Hamilton Tiger-Cat and Jay Roberts, an Ottawa Roughrider both had a history of repeated concussions during their careers and showed the characteristic signs of Chronic Traumatic Encephalopathy -- an abnormal build-up of a protein called Tau in the brain, and other degenerative changes, the study says. Chronic Traumatic Encephalopathy may eventually progress to full-blown dementia, but the researchers emphasize that the precise relationship between concussions and neurodegeneration remains to be demonstrated by research. Peter Ribbins, a former Winnipeg Blue Bomber, died at age 63 of Parkinson's disease but an autopsy showed he did not have signs of Chronic Traumatic Encephalopathy. Tony Proudfoot, an all-star defensive back for the Montreal Alouettes, died at age 61 of Lou Gehrig's disease. Although a connection between Amyotrophic lateral sclerosis and repeated head trauma is being researched, Proudfoot did not have signs of Chronic Traumatic Encephalopathy, Hazrati says.