Children with a history of asthma and various allergies may be at higher risk of developing ADHD (attention deficit hyperactivity disorder), according to a study published in the journal Annals of Allergy, Asthma and Immunology.
Researchers from Boston and the Netherlands conducted a case-control study among boys from the UK General Practice Research Database (GPRD). The study authors analyzed 884 boys with ADHD, and 3,536 boys without the disorder.
Results of the analysis showed that of the boys with ADHD, 34% suffered from asthma and 35% had a type of allergic disorder.
Compared to boys without ADHD, those who did have the diagnosis were more likely to have:
- A medical history of asthma
- Prescriptions for antihistamines.
The study found that other common exposures more apparent in ADHD sufferers were cow's milk intolerance, and prescriptions from the drug categories - antiasthmatics, respiratory corticosteroids, topical steroids, antibacterials, and antifungals.
The study authors comment:
"Despite possible limitations inherent to observational studies, this study lends support to the emerging evidence that childhood ADHD is associated with atopic diseases and impetigo."
According to the American College of Allergy, Asthma and Immunology (ACAAI), asthma and allergies commonly run in families.
They state that if both parents have an allergy, the child has a 75% chance of developing an allergy, compared to a 10-15% chance if neither parent has a an allergy. Asthma is also linked to allergic disorders, with between 60 and 80% of children with asthma also suffering from allergies.
Previous research, from the Medical Research Council (MRC) Centre at Cardiff University in Wales, says that genetics plays a role in ADHD.
The authors of this most recent study say that further research is needed to understand the underlying mechanisms of the link between ADHD and allergies, and medication for these, as well as to evaluate targeted preventive, diagnostic and therapeutic interventions.
Gailen Marchall, editor-in-chief of Annals of Allergy, Asthma and Immunology, warns that this research should not deter asthma and allergy sufferers from taking their medication. He says:
"Further research is needed to understand why there appears to be an increased risk of developing ADHD in children with allergy and asthma.
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."