Hi, GTC - those scores are nicely solid gt (mg I think but still gt, right?) And further, he is *only* 6. Retesting a bit older might be the way to go - when the adhd might be better under control or shown as more of an age related high-energy thing (seems to be what's up with our ds8).
I think block design at '16' could indicate that he got every single one right, but took his time. Did the tester say anything about that (points off during for going over limit, I think highest speed+fully complete on that one is 19, but Dottie, others can correct me if wrong).
This is an interesting read:
http://www.gifteddevelopment.com/About_GDC/whoaregiftd.htm

and I have another link of interest, but can't find it now, I will post back.