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Brief Report: Whole Blood Serotonin Levels and Gastrointestinal Symptoms in Autism Spectrum Disorder.

TitleBrief Report: Whole Blood Serotonin Levels and Gastrointestinal Symptoms in Autism Spectrum Disorder.
Publication TypeJournal Article
Year of Publication2015
AuthorsMarler, S, Ferguson, BJ, Lee, EBatey, Peters, B, Williams, K, McDonnell, E, Macklin, EA, Levitt, P, Gillespie, CHagan, Anderson, GM, Margolis, KGross, Beversdorf, DQ, Veenstra-VanderWeele, J
JournalJournal of Autism and Developmental Disorders
Date Published2015 Nov 2

Elevated whole blood serotonin levels are observed in more than 25 % of children with autism spectrum disorder (ASD). Co-occurring gastrointestinal (GI) symptoms are also common in ASD but have not previously been examined in relationship with hyperserotonemia, despite the synthesis of serotonin in the gut. In 82 children and adolescents with ASD, we observed a correlation between a quantitative measure of lower GI symptoms and whole blood serotonin levels. No significant association was seen between functional constipation diagnosis and serotonin levels in the hyperserotonemia range, suggesting that this correlation is not driven by a single subgroup. More specific assessment of gut function, including the microbiome, will be necessary to evaluate the contribution of gut physiology to serotonin levels in ASD.


Lead Author
Sarah Marler

Study Aims and Objectives
To understand the relationship between serotonin levels and digestive problems in children with Autism Spectrum Disorder (ASD).

Methods - Sample, Procedure, Study Measures, Analysis
Sensory symptoms, behavior, speech, and anxiety were assessed in 82 children ASD using caregiver reports. Both male and female subjects were included in the study, and all subjects were between the ages of 6 and 18. Beyond the results of these reports, levels of serotonin and a protein that causes inflammation were measured in the subject’s blood. Digestive troubles in the subjects were also recorded.

Results – Main Finding(s)
23% of the subjects had very high levels of serotonin. While constipation was the most common digestive problem of the children in this study, no association was found between high levels of serotonin and constipation or behavioral problems. Furthermore, no relationship was found between levels of serotonin in the blood and levels of an inflammatory protein that was also measured.

Conclusion – Summary Statement
There was no evidence in this study for the existence of a subgroup of children with ASD who have both high levels of serotonin and constipation. Furthermore, these results do not definitively support the idea that constipation leads to increased serotonin production or that heightened levels of serotonin may be used to predict digestive issues. However as both increased serotonin and constipation were found in many of the subjects, future work in this area should be done.

Alternate JournalJ Autism Dev Disord
PubMed ID26527110