O.J. Simpson watches his former defense attorney Yale Galanter testify during an evidentiary hearing in Clark County District Court in Las Vegas in 2013. Reuters

Hall of Fame running back O.J. Simpson may be suffering from a degenerative brain disease, according to the first person to discover chronic traumatic encephalopathy in the brains of deceased football players and the subject of the movie "Concussion." Dr. Bennet Omalu has never treated Simpson, but he said he is confident the 68-year-old former NFL star serving nine to 33 years in prison for a 2008 kidnapping and armed robbery conviction is not well.

"I would bet my medical license that he has CTE. Given his profile, I think it's not an irresponsible conclusion to suspect he has CTE," he told ABC News.

Omalu was portrayed by superstar actor Will Smith in the film "Concussion," which focuses on head injuries and has been blasted by the NFL. Simpson spent 11 NFL seasons with the Buffalo Bills and the San Francisco 49ers, scoring 75 total touchdowns.

Simpson was famously acquitted of murder charges in 1995 after the killings of his ex-wife, Nicole Brown Simpson, and Ron Goldman. Simpson did lose a wrongful death civil suit brought against him by the Goldman and Brown families and was forced to pay $33.5 million in damages.

He was later convicted in Nevada on unrelated kidnapping and armed robbery charges. Simpson cited CTE as a defense prior to his 2008 conviction.

“He was exposed to thousands of blunt force trauma of his brain,” Omalu said this week, renewing debate over Simpson's motives and actions. “I think because of our intoxication with football we are in some type of delusional denial. But that is how serious this is.”

CTE is believed to be caused by repeated blows to the head. It has been found in many athletes who play contact sports, such as football. CTE can only be confirmed after death via an examination of brain tissue. NFL players such as Frank Gifford and Junior Seau have been diagnosed with CTE after their deaths.

The NFL released data Friday showing that 271 concussions were diagnosed in 2015, the highest in the last four years, NBC Sports reported.