One of the main reasons some of the stimulant meds don't work effectively is that they don't cover every essential neurotransmitter system necessary for efficient pre-frontal cortical communication.
Allergists focus on traditional medical issues of acuity, life and death. IgG issues most often arise in the evaluation of chronic illness that often presents as refractory mental problems - like ADHD.
Each one of these 4 neurotransmitters in this list is associated with a link that will take you further down the ADHD neuronal/glial communication path.