By the time he is ten, he is not only no longer being schooled at all, but he has no other people around him at all - he is completely alone.
Would he forget how to write? How to read? Or would those skills still be there, albeit very rusty?
Related, would he forget a lot of words, or lose the ability to speak clearly altogether? Say he speaks to himself from time time - would he simply lose the habit? Or would he lose the knowledge of how to form words altogether?
I've really found nothing on google that wasn't about brain damage or a from-birth issue, so I'm either not hitting on the right words to use, or there's just not much out there.
ETA: I was so unclear - sheesh! I meant to say - six or seven years later, would he...etc. *rolls eyes*.