Delayed gratifications is typically a difficult concept for ADHD kids, but being gifted allows them to compensate in certain areas. He may not have ADHD at all. Have you looked at the Vanderbilt scale?
http://www.myadhd.com/vanderbiltparent6175.html. While gifted kids exhibit some ADHD symptoms, there are some differences. I see the lack of impulse control as a red flag, personally. "Meltdowns" or tantrums in front of peers with any sort of regularity is a pretty big problem. Does he have these meltdowns in other frustrating situations?
