I see that I cross-posted with Polarbear!

Here is another link that I found that is interesting:

SENG article on Misdiagnosis and Dual Diagnosis of Gifted Children

Quote
To further complicate matters, my own clinical observation suggests that about three percent of highly gifted children suffer from a functional borderline hypoglycemic condition. Silverman (1993) has suggested that perhaps the same percentage also suffer from allergies of various kinds. Physical reactions in these conditions, when combined with the intensity and sensitivity, result in behaviors that can mimic ADHD. However, the ADHD-like symptoms in such cases will vary with the time of day, length of time since last meal, type of foods eaten, or exposure to other environmental agents.

Mom to DS12 and DD3