‘Old Friends’ and learning to be friendly: How hygiene and social contact may affect the early-life gut microbiome and socioemotional development

Abstract

The human gut microbiome is a fundamental factor in human health and wellbeing. The development of the microbiome during early infancy is a critical process that has long-term implications for brain development and social behaviour. However, modern life may be limiting exposure to important microbes due to decreased contact with a wide range of microorganisms. The unique circumstances of the COVID-19 pandemic further disrupted exposure, with increased hygiene practices and physical distancing policies limiting exposure to diverse microbes. The current study aimed to investigate the association between hygiene practices and social contact with features of the gut microbiome and metabolome in infants and their potential impact on socioemotional outcomes. Results showed that changes in social contact and hygiene practices associated with the diversity, composition and metabolomic environment of the gut microbiome in infants and there was evidence that changes in the gut microbiome associate with socioemotional development at 1 year of age. Additionally, the effect of hygiene practices on the microbiome was less than expected, while social contact proved to be a much more influential variable for the 3-month microbiome. Our findings suggest that the connections between early social interactions, the gut microbiome, and socioemotional development are complex, with social contact having a more significant impact than previously anticipated.