Jules Bianchi's father Philippe says he is now more pessimistic about the chances of his son recovering from the injuries he suffered at the Japanese Grand Prix last year.
The former Marussia driver remains in a coma in a Nice hospital nine months after his accident at Suzuka.
His family remain at his bedside but, in an interview with France Info on Monday, Philippe Bianchi said he was not encouraged by the current situation.
"It's unbearable, it's a daily torture," Philippe Bianchi said. "We sometimes feel like we're going crazy, because for me, it certainly is more terrible than if he had died.
"For we're not able to help him more than we can."
No significant progress
Recovering from an accident like Bianchi's normally requires significant improvement within the first six months, something that has not happened in this case.
And although Philippe reveals that his son has been able to grasp the hand of people standing next to him, he is unsure if it is a conscious behaviour or just a reflex.
"Time goes by and I am now less optimistic than I may have been two or three months after the crash, when we could hope for a better evolution," he explained.
He added: "At some point, you need to be well-grounded and realise how serious the situation is."
While emerging from his coma may be a miracle in itself for Bianchi, his father says that could open up fresh complications.
"If he finds himself with huge disabilities, we're pretty sure it's not at all what Jules would want," he said.
"We had talked about it. He told us that if he were to have an accident similar to Michael Schumacher's, if he were even just not to be able to drive anymore, it would be very hard for him to accept it. Because it was his life."