Development of the gut microbiota throughout the first year of life and its association with socio-emotional development into childhood

Early life is a critical window for development of the gut microbiota and central nervous system, which are interconnected through the gut–brain axis. Early life gut-brain-axis connections are often studied through crosssectional cohorts, limiting insights into temporal developmental trajectories.In this talk i will present results from the PRIDE (pregnancy and infant development) BIOME study (n = 81, n = 42 males), a focus cohort within the larger prospective PRIDE study. This longitudinal study assessed whether gut microbial development during infancy is associated with socio-emotional development into childhood. Gut microbiota was assessed at 2, 4, 6, 9, and 12 months using V4 16S rRNA sequencing, and socio-emotional development was measured eight times between 6 months and 5 years using the Ages and Stages Questionnaire: Social-Emotional (ASQ-SE). Individual socio-emotional trajectories were modeled as ASQ slopes. Associations of time, ASQ slope, and their interaction with microbial diversity and taxonomy were assessed using mixed-effects models and PERMANOVA, adjusting for sex, birth weight, gestational age, and sequencing depth. ASQ slope significantly predicted beta diversity (F(1,394) = 25.90, p = 0.001) and Bifidobacterium abundance (b = −0.745, SE = 0.24, pFDR = 0.023). A significant ASQ slope × time interaction was observed for Eggerthella (b = 0.709, SE = 0.21, pFDR = 0.009): abundance decreased over time overall, but not in infants with later socio-emotional concerns. These findings identify Bifidobacterium and Eggerthella as early-life microbial correlates of socio-emotional development and potential candidates for studying healthy gut–brain development.