With the increase in the number of children diagnosed with ADHD come questions as to why. Although it is generally accepted that ADHD is, in many cases, passed along from generation to generation, scientists continually look for more answers - what are the exact causes of ADHD? Why do some children without a family history of ADHD develop it? Do other conditions contribute to the increase in diagnosis? While all these questions are a long way from being answered, researchers recently documented a link between allergies/asthma in children and ADHD.
Previous Research on the Connection Between ADHD and Allergies
Previous studies have looked into a possible correlation between ADHD and allergies; the number of diagnosis of allergic diseases has also risen dramatically. According to a study published in 2011 and completed at the University of Bangkok Metropolis, "There were increased rates of allergic sensitization and allergic rhinitis (hay fever) in ADHD children."  Other studies have shown a possible correlation between allergy diseases and ADHD. Even so, Dr. David Goodman, director of the Adult Attention Deficit Disorder of Maryland states, the research is in no way conclusive or definitive." 
A new study, published in the journal Annals of Allergy, Asthma and Immunology found that children with asthma and allergies have a higher incident rate of ADHD. Researchers looked at the medical records of about 4,500 boys in the United Kingdom (UK). Of the participants, 884 boys were diagnosed with ADHD and 3,536 did not have ADHD. The study found that approximately one-third of the boys with ADHD also suffered from asthma and/or an allergic disorder.
Specifically, those with ADHD were more likely to:
- Have a medical history of asthma
- Have a diagnosis of impetigo
- Have prescriptions for antihistamines
In addition, the boys with ADHD had a higher rate of intolerance to cow's milk and prescriptions for other medications for allergic reactions, such as antiasthmatics, respiratory corticosteriods, topical steroids, antibacterials and antifungals. The study authors believe this research adds to the increasing evidence of an association between ADHD and atopic diseases and impetigo. 
Cause or Effect?
Many parents of children with ADHD and allergies report that symptoms of ADHD worsen when their child is exposed to certain allergens, such as pollen. During times of the year when allergies flare up, the inability to focus greatly decreases for some children. This adds the question of whether ADHD and allergies are connected or whether ADHD like symptoms appear because of the symptoms of allergies or as a side effect of medications. The author of a study, completed in 2004, stated, "Nasal obstruction and other symptoms of allergic rhinitis could explain some of the cognitive patterns observed in ADHD, which might result from sleep disturbance known to occur with allergic rhinitis." 
The recent study suggests that medications used to treat allergic disorders may be the cause of ADHD symptoms, however, the editor-in-chief of Annals of Allergy, Asthma and Immunology, who published the study cautions, "Medications for these conditions far outweigh the risks and can be life-saving in some conditions. Treatment should not be stopped unless advised by a board-certified allergist." 
The best course of action, if your child has allergies and ADHD, is to talk with your child's doctors and work on a treatment plan that will incorporate both diagnosis and keep your child safe.
 "ADHD More Likely in Children with Asthma or Allergies," 2013, Aug. 16, Honor Whiteman, Medical News Today
 "ADHD Risk in Children Linked to Allergies, Asthma," 2013, Aug. 14, Rick Nauert, PsychCentral.com
 "Allergic Rhinitis in Children with Attention-Deficit/Hyperactivity Disorder," 2004, June, A. Brawley et al, Annals of Allergy, Asthma and Immunology
 "Association Between Allergic Sensitization and Attention Deficit Hyperactivity Disorder (ADHD)," 20122, March 29, P. Suwan, D. Akaramethathip and P. Noipayak, Aisan Pacific Journal of Allergy Immunology
 "Study: Lids with Eczema More Likely to Have ADHD," 2009, Feb, 18, Anne Harding, CNN Health