Typically, the presence of this sign is because the child feels like no one listens or seems to care about what he thinks and feels. Even worse, those who act like they cared do nothing but tell him what he should think and how he should feel. He tried telling them what he thought. They said things like, "You don't really believe that do you?" "That's a stupid thing to think." "You shouldn't feel that way."
Does he see things this way at home? Asking him is a place to start. When you ask him, be sure you are ready for the answer. Your getting upset or telling him he is wrong will only prove to him he is not wrong.
Ask him questions about day-to-day things and show him you are interested in him, what he thinks, and how he feels.
Do not push him to talk. His relationship with you is on his terms. Talk to him about day-to-day kinds of things but do not expect him to respond. You are there and interested and accept the reality he will talk to you when he wants to talk. In the meantime, you can offer to play games and do things where he does not need to talk.