Infant Gut Microbiome Associated with Cognitive Development

Studies in rodents provide compelling evidence that microorganisms inhabiting the gut influence neurodevelopment. In particular, experimental manipulations that alter intestinal microbiota impact exploratory and communicative behaviors and cognitive performance. In humans, the first years of life are a dynamic time in gut colonization and brain development, but little is known about the relationship between these two processes.

We tested whether microbial composition at 1 year of age is associated with cognitive outcomes using the Mullen Scales of Early Learning and with global and regional brain volumes using structural MRI at 1 and 2 years of age. Fecal samples were collected from 89 typically developing one-year-old infants. 16S rRNA amplicon sequencing was used for identification and relative quantification of bacterial taxa.

Cluster analysis identified 3 groups of infants defined by their bacterial composition. Mullen scores at age 2 differed significantly between clusters. In addition, higher alpha diversity was associated with lower scores on the overall composite score, visual reception scale, and expressive language scale at age 2. Exploratory analyses of neuroimaging data suggest the gut microbiome has minimal effects on regional brain volumes 1 and 2 years of age.

This is the first study to demonstrate associations between the gut microbiota and cognition in human infants. As such, it represents an essential first step in translating animal data into the clinic.