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

Abstract

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.

Keywords: 5-HT; Autism Treatment Network; Gastrointestinal (GI); IL-6; Medical comorbidities; Serotonin.

Conflict of interest statement

Conflict of interest The other authors report no conflicts of interests.

Figures

Fig. 1

Distribution of whole blood serotonin (5-HT). Frequency distribution of 5-HT levels, in absolute values (ng/mL) and in Z scores. 23 % of the participants had 5-HT levels two standard deviations above the mean for their race and pubertal status. N = 82

Fig. 2

Correlation between QPGS Rome III lower GI scores and log-transformed whole blood serotonin raw scores. When considered as a continuous variable in the Caucasian-only sample, with age and sex as covariates, a trend-level Pearson’s correlation (r = 0.21, p = 0.066) and a marginally significant Spearman’s correlation (ρ = 0.23, p = 0.048) were observed