Is Baby’s Gut Bacteria Related to Cognitive Development?

Sourced from: www.metagenicsinstitute.com/articles/babys-gut-bacteria-influence-cognitive-ability-later/

by Bianca Garilli, ND and Ashley Jordan Ferira, PhD, RDN
During the first years of life, an infant’s gut microbiota undergoes rapid colonization, and the microbial diversity of the growing infant results from exposure to a variety of sources.1 These microbiota sources are impacted by a variety of factors, including but not limited to: genetic underpinnings, the mother’s microbiota composition, method of delivery (vaginal vs. cesarean section), hospital and birthing environment, feeding sources (breast vs. bottle), sanitation of environments exposed to, and antibiotic use.1 By 2-5 years of age, a child’s gut microbiota closely resembles that of an adult in terms of composition and diversity and is nearing its final unique microbiome fingerprint.1 Evidence indicates that this early life gut bacterial population will set the stage for influencing health and development throughout the child’s life.1
The first years of a child’s life are also considered part of the foundational period for brain development, when neural networks growth and myelination are occurring rapidly and dynamically. It is logical to think that the child’s developing gut microbiota could play a significant role in the child’s long-term neurodevelopment. Therefore, supporting a healthy and diverse gut microbiota composition during the first years of life would be critical.
A recent study in Biological Psychiatry conducted by a team of researchers from The University of North Carolina, Chapel Hill aimed to better understand how differences in gut microbial composition and diversity in infants were associated with neurodevelopmental and cognitive performance measures.2 Researchers gathered fecal samples from 89 infants aged 1 year. This was followed by an assessment of their cognitive abilities through a variety of methods at 2 years of age, along with brain imaging, which was conducted during unsedated natural sleep at both 1 and 2 years of age.2
Based on the results of the study, the researchers categorized the children into 3 distinct categories (C1, C2, C3) differentiated by the bacterial composition/clustering of their stool samples. An inverse association was observed: the infants whose stool samples contained a higher alpha diversity at 1 year of age (higher alpha diversity indicates a high number of different species present in the sample)3 had lower cognitive performances scores on the overall composite score, the visual receptions scale, and the expressive language scale.2 This was perhaps a surprising finding, since high alpha diversity is considered a more “mature” microbial composition and has been associated with positive health outcomes in adults.2
Bacterial clusters (C1, C2, C3) at 1 year of age were associated with cognitive performance at 2 years of age. Specifically:2

• C2 group: (high levels of Bacteroides) lowest alpha diversity was associated with the highest level of cognitive performance (90th percentile). C2 infants were more likely to be birthed vaginally and be breastfed, and are considered to have a less mature microbiome
• C1 group: (high levels of Faecalibacterium) highest alpha diversity was associated with the lowest level of cognitive performance (72nd percentile)
• C2 > C3 > C1 was the cluster pattern observed for the visual reception scale

A high alpha diversity is thought to indicate a more mature, adult-like community, but the concept of high vs. low alpha diversity being positive vs. negative is certainly still an active area of debate and ongoing research. This is the first study to demonstrate an association between the human gut microbiota and cognitive outcomes in developing infants; the majority of studies to date in this area have been conducted in animals.2
Future studies would benefit from incorporating multiple measurement time points for microbiota sampling and longer follow-up duration. Additionally, incorporating data on broad-spectrum metabolomics or transcriptomics would yield mechanistic insights.2 This future research is critical to understand the associations between gut bacterial composition in infants and long-term neurodevelopment and cognitive health, so that targeted interventions can be informed for future investigations.
Why is this Clinically Relevant?

• Various routes of exposure in the antenatal and postnatal period of life influence the long-term, individualized microbiota signature
• It is important to establish a healthy gut microbiota in the newborn and developing infant via:
  • Exposure to maternal vaginal flora during delivery if possible
  • Limiting antibiotic use in early years
  • Breastfeeding and maternal skin to skin contact in early months of life
• The gut microbiota diversity in infants was recently associated with measures of cognitive performance in the growing infant2
• Further research will be important to understand this association further and to one day ultimately develop targeted microbiota interventions to support healthy neurodevelopmental outcomes in children

Link to abstract
Citations

1. Rodriguez JM, Murphy K, Stanton C, et al. The composition of the gut microbiota throughout life, with an emphasis on early life. Microb Ecol Health Dis. 2015;26:26050.
2. Carlson A, Xia K, Azcarate-Peril MA, et al. Infant gut microbiome associated with cognitive development. Biological Psychiatry. 2018;83(2):148–159.
3. Research Gate. https://www.researchgate.net/post/What_is_the_difference_between_alpha-diversity_and_beta-diversity_in_microbial_ecology. Accessed February 17, 2018.