Wired posted an interesting article on how they are starting totreat battle induced psychological trauma.. Unfortunately, they don't explain the precise role the software plays in the recovery process, so we will have to speculate about that.
My impression is that the psychological trauma has more to do with what you think about what happened to you than what actually happened to you. REvisiting it in VR and developing a different perspective, may be the secret of the treatment. Since they don't tell us, the secret remains a secret.