I think he may have that or ADHD, or a combination of the two. It seems like a lot of aspects pertaining to society are foreign to him, like he questions things to Hobbes in comic strips, about life and the logic behind Santa Claus. Also, he has a notably advanced vocabulary for his age considering that he's only six years old. His imagination, like any child, tends to run wild but his imagination is perhaps more complex than the average kid, given that he pretends to crash-land on alien planets, finds himself lost in a world without the laws of perspective, and also he imagines that he travels the space-time continuum with Hobbes. He clearly displays above-average intelligence and has a unique way of perceiving the world. As for the ADHD, he daydreams a LOT during class and when his parents lecture him. Also, he's hyperactive and running around the house and playing games that he created. In addition, he seems to have trouble with resisting impulsive behaviors, as he's worried about Santa putting him on the naughty list, but he just can't help throwing a snowball at Susy Derkins. What do you guys think?