Objectives: We sought to determine whether 1) child asthma and allergies are more common in children with autism spectrum disorder (ASD) and 2) whether asthma and allergies are associated with other subphenotypes within autism.
Methods: Participants were members of the CHildhood Autism Risks from Genetics and the Environment (CHARGE) study, a large population-based case-control study. Children were 3-5 years at study enrollment. Typical development in general population controls was confirmed through scores on the Social Communication Questionnaire (SCQ), Mullen Scales of Early Learning (MSL), and the Vineland Adaptive Behavior Scales, while ASD diagnosis was confirmed through scores on the SCQ, ADOS, and ADI-R. The primary study group included typically developing controls and confirmed cases of autism spectrum disorder (ASD). We compared basic frequencies of child asthma and allergy, and types of allergies, between cases and controls, and used multivariate logistic regression to obtain crude and adjusted odds ratios of the association between the child conditions and ASD status. We also assessed whether these child conditions were associated with differences in scores on the MSL, and Aberrant Behavior Checklist (ABC) in all children, and on the ADOS and ADI-R for case children. Multivariate linear regression was used to obtain adjusted estimates of these associations within cases and overall.
Results: 553 children with ASD and 377 typically developing children were included in these analyses. Prevalence of asthma and allergy did not differ in cases and controls. When assessing conditions according to diagnostic subgroup, allergy was more common in children with a diagnosis of autistic disorder (50%) than in children with a broader ASD phenotype (40%); this association was significant in adjusted analyses, but when considering only medical-record confirmed allergy, the association was non-significant. Child asthma was not associated with scores on the MSL, ABC, ADOS, or ADI-R. Child allergy was associated with lower fine motor scores on the MSL and higher stereotypy scores on both the ABC (in all children and in case children only) and the ADI-R in crude comparisons. In adjusted analysis, child allergy was associated with a modest but significant increase in stereotypy scores, though fully adjusted results of this association utilizing only medical-record confirmed allergy were no longer significant.
Conclusions: Our results suggest that asthma and allergies are not more common in young children with autism spectrum disorder, and that the presence of these conditions does not significantly affect cognitive and behavioral scores. However, future work should further assess the preliminary association we saw with a tendency for higher stereotypy scores in case children with allergies.
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