I'm reading again this book by David Smail.
He says in the Preface that it's about the possibility of understanding the 'language' of pain. Such pain (psychological pain, emotional distress) is caused when a person is unable to abandon a fundamentally true insight into the nature of the social world in favour of a convenient illusion. Emotional distress, so understood, far from being an indication that something is wrong with the person, is far more likely to point to something wrong with his/her world.
I do notice that any attempt to attribute autism to environmental factors, to see it as rooted in the social experience of the child, is strongly resisted by the professionals. My own observation is that children on the autistic spectrum often come from peculiarly uncommunicative parents. This is not to say that the parents are to blame, or even responsible, for the child's condition. It may well be that they (the parents) are themselves 'tuning out' of painful experiences of their own.