Thank you Roses... that helped me put things in perspective.

The fact is that in other ways his functioning is improving, he now has friends, which is a massive improvement on where he was even a year ago, and in fact he's around with his mates now, bouncing on a trampoline. (Their mother just rang and said that her kids had insisted he stay for tea.)

So perhaps as well as worrying about negative things, I should also look at the positives.

And yes, he does watch science fiction, read "graphic novels" about judge dredd and the matrix, and reads philosophy books (weird, but true).

Thank you both, you punctured my anxiety nicely. I'll still keep an eye out, but I'll not automatically assume the worst.