Paris - Marc Dal Maso who won two Five Nations Grand Slams with France and was a coach for Japan at this year's Rugby World Cup announced on Monday that he has Parkinson's Disease.
Dal Maso, 48, said he did not have the degenerative disorder through "chance".
He told the Midi-Olympique rugby daily: "Let's just say there are sports which help illnesses like this and rugby is one of them."
Dal Maso, who coached the Japanese scrum at the World Cup when the team beat South Africa in a sparkling group campaign, said he had decided to go public because people were starting to talk.
"There were rumours doing the rounds so rather than listen to people say stupid things it was better that they know."
He said the illness had been detected in 2012 but had probably started when he was about 30.
He said he had gone to Japan "to hide" after refusing positions with Toulon and Racing Paris in France's Top 14.
Dal Maso played 33 times for France between 1988 and 2000 and was at the 1999 World Cup as well as winning the Five Nations Grand Slam in 1997 and 1998.
Dal Maso said he would act as a consultant for New Zealand's Highlanders in Super Rugby in early 2016.