Reference Work Entry

Comprehensive Guide to Autism

pp 1995-2013

ASD and Food Allergy

  • Harumi JyonouchiAffiliated withDepartment of Pediatrics, University of Medicine and Dentistry - New Jersey Medical School, F570A, MSB Email author 

Abstract

Autism spectrum disorders (ASD) is defined and diagnosed by behavioral symptoms, except for a small subset of ASD children with known gene mutations. As a result, ASD children are characterized by varying clinical manifestations as well as a spectrum of co-morbid conditions, with gastrointestinal (GI) symptoms being one of the most common. Some, but not all of the ASD children with GI symptoms reveal favorable responses to the restricted diet (RD) which is typically, a casein-free, gluten free (cf/gf) diet. This has led to speculation that food allergy (FA) plays a role in the GI symptoms observed in ASD children. However, diagnosis and management of FA is not as straight-forward as it may seem, especially in children with limited expressive languages. Currently, the role of FA in ASD children with GI symptoms remains controversial.

FA, adverse reactions to food caused by immune mechanisms, is mediated by both immunoglobulin (Ig) E and non-IgE mediated mechanisms. IgE antibody (Ab) mediated FA (IFA) is characterized by immediate, potentially fatal, allergic reactions. While non-IgE mediated FA (NFA) are typically delayed type reactions that are limited to the GI tract. Unlike IFA, NFA diagnosis is currently solely based on clinical findings. This is due to a lack of laboratory diagnostic measures. For IFA, laboratory measures are available for detecting food allergen specific IgE; prick skin testing (PST) and enzyme linked immunosorbent assay (ELISA) for allergen specific serum IgE. However, PST and ELISA for allergen specific IgE are well known to yield false positive results at high frequency for food allergens. In addition, the presence of neuropsychiatric symptoms, limited expressive language, and symptoms of dysautonomia which are commonly seen in ASD children, make it even more difficult to diagnose FA in ASD children.

This first part of this chapter will describe current diagnostic/management guidelines of FA, its varying clinical presentations, and environmental factors that affect development of FA. The second part of this chapter will discuss currently known facts regarding FA in ASD children, which is rather scant. In addition, the challenges that primary physicians are likely to face in diagnosis/management of FA in ASD children will also be discussed.