ADHD Associated with Food, Skin and Respiratory Allergy

A recent investigation into children with attention deficit/hyperactivity disorder (ADHD) found significant associations between the condition and common allergic conditions such as food allergy, respiratory allergy, and skin allergy.

Prior studies have predominantly considered the associations of respiratory allergy and skin allergy in patients with ADHD. However, little is known of the association between food allergy and ADHD, and available data on the subject had been inconsistent.

Investigators led by Buyun Liu, MD, PhD, Department of Epidemiology at the University of Iowa, suggested that the inconsistent findings could have been partly due to limited sample sizes and statistical power.

As such, Liu and colleagues analyzed large-sclae and nationally representative data to determine association of food allergy and other allergic conditions with ADHD in children in the United States.

The Methods

The team utilized data from the National Health Interview Survey (NHIS), a leading health survey that is conducted annually by the National Center for Health Statistics at the Centers for Disease Control and Prevention (CDC).

The survey included detailed health-related information pertaining to physical and mental health, and allergic conditions were defined based on responses to several questions.

The questions, which were addressed to parents and guardians, included the following:

“During the past 12 months, has [your child] had (1) any kind of food or digestive allergy; (2) any kind of respiratory allergy; (3) eczema or any kind of skin allergy?”

ADHD was defined based on an affirmative response to the question: “Has a doctor or health professional ever told you that [your child] had Attention Deficit Hyperactivity Disorder (ADHD) or Attention Deficit Disorder (ADD)?”

Additional demographic data, including age, sex, race/ethnicity, sex, education, family income, and geographic region were collected using standardized questionnaires featured in the interview.

All data analyses were conducted using the survey procedures of SAS 9.4 (SAS Institute Inc., Cary, NC, USA), and 2-sided p < 0.05 was considered statistically significant.

The Results

A total of 192,573 children aged 4-17 years old were included in the analysis. Among those children, 8603 had food allergy, 24,218 had respiratory allergy, and 18,703 had skin allergy.

Investigators noted that children with skin allergy were younger, more likely to be black, and they had higher family education levels than children without skin allergy, while children with respiratory allergy, compared with those without respiratory allergy, were older, more likely to be male, white, and they had higher family education levels

A diagnostic history of ADHD was reported in 15,376 children. The data gathered indicated that children with ADHD were older, more likely to be male and white, and they had lower family income levels.

The weighted prevalence of ADHD was higher among children with allergic conditions.

Among children with food allergy, ADHD prevalence was 12.66% (95% CI 11.57–13.75) compared to those without ADHD (7.99&, 95% CI 7.82–8.15) (p < 0.001)

Likewise, ADHA prevelance was 12.16% (95% CI 11.60–12.72) vs. 7.63% (95% CI 7.46–7.80) among children with and without respiratory allergy (p < 0.001), and 11.46% (95% CI 10.90–12.01) vs. 7.83% (95% CI 7.66–8.01) among children with and without skin allergy (p < 0.001).

Liu and colleagues added that their study extended findings on allergic conditions and ADHD, with insights on food allergy.

“Although the detailed mechanisms linking food allergy and other allergic conditions to ADHD remain to be understood, physicians should be aware of the increased risk of ADHD as a comorbidity of children with allergic conditions,” the team wrote.

The study, "Association of Food Allergy, Respiratory Allergy, and Skin Allergy with Attention Deficit/Hyperactivity Disorder among Children," was published online in Nutrients.