His mother Jamie says she noticed her son was having problems in preschool, such as "freaking out" when his teachers put his hands in finger paint or when he'd lie down in the corner.

WSJ: ADHD Warning Signs and Kids: Growing Pains or Cause for Concern?

We finger-paint -- that's a really fun one -- and it's amazing what you see.

CNN: Mendes giving sick children a creative outlet

And when you finger-paint with a kid or you dance and you see their little eyes light up, it's pretty incredible.

CNN: Mendes giving sick children a creative outlet