Clinical Correlates for Seizure Disorder, Asthma, and Allergies in Youth with ASD Versus Psychiatric Referrals

Background:  In this study we sought to compare rates of three relatively common co-occurring medical conditions known to add to caregiver burden in a large group of children with autism spectrum disorder (ASD) and a comparison sample of non-ASD neuro-atypical psychiatric outpatient referrals. Such a comparison would address at least in part the question of whether the seemingly higher rates of these conditions was peculiar to ASD or more generally associated with CNS dysfunction. Equally important was the desire to determine if the clinical correlates of these medical conditions differed in these two groups of youth, which would suggest that the biologic substrates of neurobehavioral syndromes and co-occurring medical conditions interact to result in unique clinical presentations.

Objectives:  To examine comparative rates of seizure disorder, asthma, and allergy in youth with ASD versus typically developing peers and their association with clinical correlates and other types of psychopathology.

Methods:  This study examined the rates of these conditions in a large sample of consecutively referred youth with ASD (n=521) and an equally large sample of youth referred for psychiatric outpatient evaluation (n=653). Caregivers completed a developmental history questionnaire (parents) and a well-validated psychiatric symptom severity and impairment rating scale (parents, teachers).

Results:  Rates of seizure disorder and allergies, but not asthma, were significantly higher in the ASD group than psychiatric referrals (Figure 1, Panel A), and this was also case when the groups were limited to children (6-12 years) with IQs ≥70 (Figure 1, Panel B). In the total sample, approximately one fourth (23%) of youth with ASD with either allergies or asthma had both disorders, and the rate of co-occurrence was higher for the comparison group (33%) (Figure 2). Within each diagnostic group, there were no differences in ASD severity between children with or without epilepsy, asthma, or allergy; however, there were significant interactions for epilepsy (repetitive behaviors) and asthma (communication). In the ASD sample, children with epilepsy had more severe schizophrenia symptoms, and psychiatric referrals with allergy had more anxiety and depression symptoms (parent’s ratings) but lesssevere aggression (teachers’ ratings). Epilepsy and asthma associations with treatment (i.e., psychotropic medication, special education) were unique to ASD; youth with ASD and epilepsy were more likely be receiving these treatments than ASD youth without epilepsy, though for non-ASD youth treatment did not differ for those with and without epilepsy. In the ASD sample, youth with asthma less often received special education, but no such association was present in non-ASD psychiatric referrals.

Conclusions:  Compared with a heterogeneous group of non-ASD neuro-atypicals, youth with ASD are at differentially greater risk for seizure disorder and allergy. Furthermore, youth with ASD with and without seizure disorder, asthma, or epilepsy evidence a different pattern of associations with clinically relevant (e.g., psychiatric symptoms) and ecologically valid variables (e.g., treatment), and these relations vary depending on the type of co-occurring illness, all of which underscores the value of considering the notion of unique clinical presentations within neurodevelopmental disorders for furthering our understanding of nosology.