For more than ten years, doctors, researchers and experts have searched for scientific proof that ADHD is a disease. To date, there currently is none. What has been noted is that in a stsudy by Castellano, 93% of children that had ADHD symptoms Baughman noted that 93% of the subjects in the study by Castellano showing that ADHD children had 5% smaller brains were on chronic stimulation therapy (Ritalin and related drugs). Hence the possibility that the stimulant drugs caused the condition.