Updated

Scientists have found evidence connecting head injuries in athletes to Lou Gehrig's disease, according to a report to air on HBO's "Real Sports" on Tuesday night.

Dr. Ann McKee said in an interview with the television magazine show that she found toxic proteins in the spinal cords of three athletes who had suffered head injuries and then later died of Lou Gehrig's disease, or ALS. Those same proteins have been found in the brains of athletes with chronic traumatic encephalopathy (CTE), a disease linked to head injuries that causes cognitive decline, abnormal behavior and dementia.

The findings are to be published in the Journal of Neuropathology and Experimental Neurology.

McKee, a neurology professor at Boston University who has studied CTE in athletes, noticed that an unusually high number of football players seemed to be affected by ALS. The disease attacks nerve cells in the brain and spinal cord, and destroys the ability to move and speak.

She was able to study the brains and spinal cords of ex-Minnesota Vikings linebacker Wally Hilgenberg, former Southern California linebacker Eric Scoggins, and a boxer whose family asked that his name be kept private.

She found the toxic proteins in the spines of all three. The proteins were not present in the spines of athletes with CTE who didn't have Lou Gehrig's disease. Nor had she seen them in non-athletes who died of ALS.