The stunning revelations from the Portuguese boss come as Spanish giants Real Madrid continue their pursuit of the 24-year-old.
Real are said to have made a world record transfer bid to lure the Welsh winger to the Spanish capital, and all indications are that he is keen to join the Liga giants.
But Tottenham are standing firm in their negotiations, with club chairman Daniel Levy determined to keep Bale at the club as they bid to qualify for the UEFA Champions League.
Bale's thoughts appear to be clear though, with Villas-Boas revealing that the winger will simply not discuss the situation with anyone at White Hart Lane.
Villas-Boas said: "His mental state nobody knows, because the player doesn't speak.
"The only thing that we are able to see is the player arriving in and out of the training ground. It's fine."
Villas-Boas also confirmed on Thursday that Bale would miss Sunday's Premier League season opener at newly promoted Crystal Palace.
Bale – who scored 21 Premier League goals last term – is set for a longer stint on the sidelines as he continues to battle an apparent foot injury.
