Autism spectrum disorders (ASD) are commonly associated with gastrointestinal (GI) symptoms such as constipation, irritable bowel syndrome, abdominal pain and diarrhea, among others. Moreover, the higher occurrence of GI tract symptoms in this patient population has been associated with increased levels of the stress hormone cortisol, in response to acute stressors[1]. Researchers from the University of Missouri School Of Medicine investigated whether individual nutritional intake contributed to the relationship between the stress response and GI functioning in ASD patients.

The population surveyed consisted of 75 ASD patients between the ages of 5 and 18 years recruited from the Autism Speaks – Autism Treatment Network[2] at the University of Missouri Thompson Center for Autism & Neurodevelopmental Disorders. The Questionnaire on Pediatric Gastrointestinal Symptoms – Rome III (QPGS-RIII), a 71-item parent report, was used to assess GI dysfunction, providing separate scores for upper and lower GI tract symptoms. Next, dietary composition was assessed using a Food Frequency Questionnaire in which parents estimated the participant’s food intake over the previous month. Nutrient information was obtained for each item consumed according to the USDA Food Composition Database[3]. The individuals also underwent two laboratory assessments to measure cortisol levels in response to acute stressors.

They found:

  • The most frequently occurring GI symptoms, according to parental report on the QPGS-RIII, were constipation (42.5%), irritable bowel syndrome (11.7%), lower abdominal pain associated with bowel symptoms (9.2%) and upper pain associated with bowel symptoms (7.5%)
  • A significant, positive, correlation was found between cortisol response to stress and QPGS-RIII lower GI tract scores
    • This association was greater for children with a history of regressive ASD
  • Nutritional composition, when adjusted for the 32 nutrients examined in the study, was not associated with upper or lower GI tract symptoms in this sample of individuals with ASD

The authors conclude that diet is likely not a driving factor for the previously observed relationship between stress response and GI functioning in the ASD population tested. These findings, therefore, support the hypothesis that there may be other factors related to lower GI tract disorders in ASD and that further studies need to be done to explore additional associations.

An important consideration is that the study utilizes correlational comparisons between reported intake of 32 different dietary parameters found in a standard diet, stress response and GI outcomes. At this point, causal relationships are not able to be made from these analyses and further studies are warranted. Furthermore, food frequency questionnaires, although informative, are possibly not a sensitive tool to measure dietary intake as patients or parents may not accurately recall full contents of meals, snacks or portion sizes spanning the previous month.

Why is this Clinically Relevant?

  • According to a 2014 surveillance study conducted by the Centers for Disease Control and Prevention, 1 in 68 children are diagnosed as having autism spectrum disorder (ASD) with higher prevalence observed in boys (1 in 42 versus 1 in 189 girls)[4]
  • The exact underlying mechanisms and etiology of ASD are still unknown and available effective therapies are limited
  • Gastrointestinal symptoms are commonly reported in ASD children and adolescents but the relationship between GI distress, nutrient intake and ASD remains poorly understood
  • Many patients with ASD try gluten-free and casein-free diets and this may also impact GI symptomatology or nutritional status
  • While caution should be exercised while interpreting correlational data, this study highlights the importance of incorporating stress management strategies into current ASD therapeutic interventions

References

The study “Associations between Dietary Composition and Gastrointestinal Symptoms in Autism Spectrum Disorder” was recently presented at the 2017 International Meeting for Autism Research

[1] Ferguson, B.J., Marler, S., Altstein, L.L., Lee, E.B., Mazurek, M.O., McLaughlin, A.,Macklin, E.A., McDonnell, E., Davis, D.J., Belenchia, A.M., Gillespie, C.H., Peterson, C.A., Bauman, M.L.,Margolis, K.G., Veenstra-VanderWeele, J., Beversdorf, D.Q., Associations between cytokines, endocrine stress response, and gastrointestinal symptoms in autism spectrum disorder, Brain, Behavior, and Immunity (2016), doi: http://dx.doi.org/10.1016/j.bbi.2016.05.009

[2] https://www.autismspeaks.org/science/resources-programs/autism-treatment-network

[3] https://ndb.nal.usda.gov/ndb/

[4] https://www.autismspeaks.org/what-autism/prevalence

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