03.25.2015
by Molly Walker
Contributing Writer
Action Points
- Note that this observational study demonstrated an association between autism spectrum disorder and maternally reported gastrointestinal symptoms.
- Be aware that the study’s reliance on maternal report could significantly bias the results.
Children who were diagnosed with autism spectrum disorder (ASD) were more likely to have maternally reported gastrointestinal symptoms in their first years of life compared to children with typical development, according to a population-based study from Norway.
Mothers of children with ASD were more likely to report their children experienced constipation and food allergies/intolerance both at 6 to 18 months (adjusted OR 2.7, 95% CI 1.9-3.8; P<0.001 and aOR 1.7, 95% CI 1.1-2.6; P=0.01, respectively), versus normal children in the study, reported Michaeline Bresnahan, PhD, MPH, department of epidemiology at the Mailman School of Public Health, Columbia University in New York City, and colleagues.
Similar findings were seen at 18 to 36 months (aOR 1.6, 95% CI, 1.2-2.3; P<0.01 and aOR 2.0, 95% CI 1.3-3.1; P<0.01), respectively, for ASD and normal children. Diarrhea was also more likely to be reported for children with ASD at 18 to 36 months (aOR, 2.3, 95% CI 1.5-3.6; P<0.001) than children with typical development, the researchers reported in JAMA Psychiatry.
In fact, the odds of maternally reported GI symptoms for children with ASD increased as children grew older. Mothers of 18- to 36-month old children with ASD were associated with “a 2-fold increased odds of reporting any GI symptom compared with children with typical development” (aOR 2.1, 95% CI 1.6-2.8; P<0.001. These adjusted odds ratios were slightly lower in mothers of 6 to 18-month old autistic children (aOR 1.4, 95% CI 1.1-1.9, P=0.01).
However, researchers note that because the questionnaire did not provide symptom definitions (such as frequency or duration) for diarrhea and constipation, the data is subject to overreporting or underreporting based on the caregiver’s own “common-sense” judgment. This could be considered a major limitation to the study. “There is little published information on the validity of maternal report of GI features in infants and toddlers with the exception of food allergy/intolerance,” they wrote.
When examining children with ASD over time (from 6 months to 36 months), they were more than twice as likely to have any maternally reported GI symptom (aOR, 2.6, 95% CI 1.8-3.7; P<0.001) — specifically constipation (aOR 3.4, 95% CI 2.1-5.5; P<0.001) and diarrhea (aOR 2.4, 95% CI 1.4-4.2) — than mothers of children with typical development.
In a separate interview with MedPage Today, Bresnahan said that the study could contribute valuable insight because of its longitudinal design. “It was widely believed that GI problems are more common in ASD, but the population-based literature seemed inconsistent, and the timing of the appearance of GI problems was not well established,” she said.
The study also examined children with developmental delays, and found those children also were at increased odds for maternally reported constipation at 6 to 18-months (aOR 1.3, 95% CI 1.2-1.5; P<0.001) and 18 to 36-months (aOR 1.3, 95% CI 1.3-3.1;P<0.001). Children with delayed development were defined as “children without ASD who exhibited mild-to-severe delays in language and/or motor skill development based on 36-month questionnaire items.”
Bresnahan’s group reviewed data from the Norwegian Mother and Child Cohort Study (MoBa) for children born from January 1, 2002 to December 31, 2008 whose mothers completed both 18-month and 36-month old questionnaires. Of the 45,126 children eligible, they compared 3 groups: children with ASD (n=195), children with delayed development (n=4,636) and children with typical development (n=40,295). A child was given a diagnosis of ASD if they had previously been diagnosed at the Autism Birth Cohort Clinic or the Norwegian Patient Registry.
Participation rates for the 18-month and 36-month questionnaires were 75% and 60%, respectively, which the authors noted as another potential limitation in terms of sample representation. They also cited the criteria used to define children with developmental delays, which may not apply to children “with more severe degrees of global impairment.”
The authors offered potential hypotheses for the association between ASD and GI symptoms, including food selectivity, shared genetic factors, metabolism and serotonergic signaling.
Bresnahan suggested that in terms of the epidemiology, the next steps in research should include evaluating dietary and phenotype data.
“Although the nature of the association remains unclear, findings from our study suggest that future research should focus on early life, with specific attention paid to the development of the enteric nervous system, innate and adaptive immunity, microbial colonization of the GI tract, and evolving feeding or dietary patterns,” the researchers concluded in their paper.
This research was supported by the Norweigan Ministry of Health and Care Services, the Norweigan Ministry of Education and Research, and the National Institutes of Health/National Institute of Neurological Disorders and Stroke.
The authors have no conflicts of interest to disclose.
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