Maternal Serotonin Levels and Neurodevelopmental Severity in Autistic Children: A Partial Replication and Extension

Objective

The serotonin system has long been implicated in autism spectrum disorder. A previous study reported lower whole blood serotonin (WB5-HT) concentrations in the mothers of children with more severe autism. This study attempted to replicate this finding in an independent cohort.

Method

A latent profile analysis was conducted in 259 children with autism using indicator variables across autistic traits, cognition, and adaptive function. In a subgroup of 162 participants with maternal WB5-HT data, maternal WB5-HT in children with the highest severity profile was compared with maternal WB5-HT in children with other profiles, both overall and across 5 quantiles of the maternal WB5-HT distribution.

Results

A latent profile analysis solution was identified that stratified participants into low-, medium-, and high-severity profiles. Although this solution was broadly similar to the prior work, the high-severity profile showed different scores in restricted and repetitive behavior, nonverbal IQ, and adaptive function. Median WB5-HT in the high-severity profile did not differ significantly from other profiles, but was lower at the 90th percentile of severity (by 59.40 ng/mL, 95% CI 6.42 to 101.51 ng/mL, adjusted p < .01). In exploratory models, maternal WB5-HT was negatively associated with social impairment.

Conclusion

In contrast to the previous study, this study did not find lower group levels of maternal WB5-HT in children with highest autism symptom severity. However, children in the high-severity group were less likely to have maternal WB5-HT values in the upper range of the distribution. This comparative absence of values in the upper range of maternal WB5-HT in this high-severity group warrants further investigation.

Plain language summary

This study explored the link between serotonin levels in mothers and the severity of autism in their children. Data analyzed from 259 autistic children drawn from the Simons Simplex Collection cohort separated them into three “latent profiles” of low, medium, and high severity.

The relation between severity profile and maternal serotonin level was assessed in a subset of 162 children for whom these data were available. Although previous work suggested that serotonin levels were overall lower in the mothers of severely affected children, the present study did not find a significant difference in overall serotonin levels. However, the present study found that fewer mothers of severely affected children had high serotonin levels, which warrants further investigation.

Diversity & Inclusion Statement

We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. We worked to ensure sex balance in the selection of non-human subjects.