Jean Todt has admitted that "communication" with Michael Schumacher is now compromised.
More than five years after the seven time world champion's French skiing accident, almost nothing is known about the extent of Schumacher's brain damage.
His former Ferrari teammate Rubens Barrichello, for example, has been forbidden from visiting the great German at his home in Switzerland.
"I tried once but the family refused," he told Express newspaper.
"They said 'you would not do yourself or him any good with this'."
Former Ferrari boss Todt, now the FIA president, is one of the select few who is welcome to visit Schumacher.
"I can only say that his family is taking good care of him and he continues to fight," the Frenchman said.
"His family is fighting just as much and of course our friendship cannot be the same as it once was," Todt added. "Just because there's no longer the same communication as before."
