The assembly of the gut microbiota starts from birth, characterised by a rapid rate of colonisation and expansion of gut bacteria dominated by Actinobacteria and Proteobacteria shifting towards a community dominated by Firmicutes and Bacteroidetes.
Experiments in animal models have shown that this process is physiologically connected with the synaptogenesis in the cerebral cortex. Seminal studies in germ-free mice emphasised that early colonisation with a complete specific-pathogen-free microbiota ameliorated brain development and behavioural abnormalities. Cross-sectional clinical studies have also associated altered microbial composition with the pathophysiology of Alzheimer’s disease, autism spectrum disorder, multiple sclerosis, Parkinson’s disease, and stroke.
In infants, this mechanistic relationship has not been empirically demonstrated but several associations between gut microbiota and behaviour have been reported. Altered microbial composition of the gut has been reported in children with autism, and been linked to childhood temperament at 18–27 months of age, as well as cognition at 2 years of age, and to communication, motor, personal and social skills.
The current study examined whether the gut microbiota was associated with infant neurodevelopment in 71 full-term healthy infants aged 18 months (45 boys and 26 girls) chosen from the panel of infants that belonged to PREOBE observational study cohort (mothers were recruited between 2007 and 2012 at the San Cecilio and Mother-Infant University Hospitals in Granada, Spain).
The researchers used 16S rRNA gene sequencing for the analysis of the infants’ gut microbiota, with stool samples taken at 18 months of age. Neurodevelopment was assessed with the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III).
Children were grouped by behavioural trait performance in above- and below-median groups for their fine motor activity.
The resulting data revealed a significant association between gut microbiota and fine motricity skills, which the authors say was robust to adjustment for infant, mother, nutritional and perinatal variables.
When controlling for maternal pre-gestational BMI and breastfeeding for up to 3 months, the examination showed that Turicibacter and Parabacteroides were highly abundant in the below-median fine motor skill group of infants. Whereas Collinsella, Coprococcus, Enterococcus, Fusobacterium, Holdemanella, Propionibacterium, Roseburia, Veillonella, Bifidobacterium and Lactobacillus were more abundant in the above-median fine motor group.
The report states: "Our study adds to the mounting evidence connecting the gut microbiota with the gut–brain axis, where the initial stages of gut colonization and assemblage may be linked with neurodevelopmental outcomes with potential long-term associations. These results suggest targeting for negatively associated species such as Turicibacter and Parabacteroides in appropriate mice models, and invite further interventional studies using Lactobacillus and Bifidobacterium strains to influence motricity outcomes in infants."
This is the first published prospective infant study linking enterotypes and infant neurodevelopment.
This is the first published prospective infant study showing poorer fine motor skill performances of infants with a Bacteroides-dominant community. These results confirm the observations by Sordillo et al. on the association of Bacteroides-dominated co-abundance grouping with poorer fine motor scores.
The present study also identified taxa whose abundance was significantly different between groups. The motricity of the below-median group was associated with increased abundances of Turicibacter and Parabacteroides. This is the first report of an association between these taxa and host behaviour in healthy infants.
Finegold et al. established a list of significant genera among severely autistic vs. non-sibling control samples, where Turicibacter and Parabacteroides were significantly increased in autistic children.
Motor coordination impairment is a common condition in children with neurodevelopmental disorders such as autism. In the present cohort, better fine motor skills were associated with increased abundances of eleven genera, including Coprococcus and an unassigned genus within Veillonellaceae. Kang et al. reported that Coprococcus and unclass Veillonellaceae were less abundant in autistic individuals compared with neurotypical controls between the ages of 3 and 16 years.
The authors of the present study say a particularly interesting finding in the above-median group was an over-abundance of Lactobacillus and Bifidobacterium, the most important and widely used probiotic genera.
Acuña I, Cerdó T, Ruiz A, et al
Infant Gut Microbiota Associated with Fine Motor Skills