NGF and attention deficit-hyperactivity disorder: Keeping in mind that ADHD is a complex, multifaceted illness and that it is critical that we understand the role allergic response plays in the etiology of the subset of children with both diseases, we devised our study to (1) promote an understanding of the synergistic effects of treatment with both antihistamines and stimulants, (2) provide insight into the pathophysiology of this illness, and (3) determine the role NGF may play in children with both ADHD and allergic rhinitis.