The development of the gut microbiome and temperament during infancy and early childhood: A systematic review

The Individual and Combined Effects of Prenatal Micronutrient Supplementations on Neurobehavioral Developmental Disorders in Preschool Children

Background: Neurobehavioral developmental disorders significantly affect children's future well-being and contribute to the global disease burden. While prenatal micronutrient supplementation is crucial for fetal neural development, their individual and combined effects on subsequent neurobehavioral outcomes in childhood remain poorly understood. This study aimed to examine the individual and combined effects of prenatal micronutrient supplementation on neurobehavioral developmental disorders in preschool children, and to explore their effects across specific developmental domains. Methods: 15,636 mother-child dyads were recruited from the 2022 children's survey in Shenzhen, China. Mothers provided information on prenatal supplementation of calcium, folic acid, iron, and multivitamins. Five domains of children's neurobehavioral functioning were assessed using the Ages and Stages Questionnaire-Third Edition (communication, gross motor, fine motor, problem-solving, and personal-social status). Logistic regression models were used to estimate the effect of micronutrient supplementations on NDDs across crude, adjusted, and full-inclusion models. Combined effects were assessed by multiplicative and additive interactions calculated from crossover analysis. Results: 11.7% of preschool children were identified as at risk for neurobehavioral developmental disorders, with the highest prevalence in the gross motor domain. Prenatal multivitamin supplementation showed a protective effect against neurobehavioral developmental disorders (OR = 0.73, 95% CI = 0.66-0.81). Interaction analysis revealed that the combination of iron and multivitamins further enhanced this protection, with both multiplicative (IOR = 1.26, 95% CI = 1.02-1.57) and additive interactions (RERI = 0.18, 95% CI = 0.02-0.35). The problem-solving domain consistently showed the greatest benefit from the supplementation of these micronutrients individually and in combination. Conclusions: Prenatal multivitamin supplementation reduces the risk of neurobehavioral developmental disorders, especially when combined with iron supplementation. These findings highlight the potential benefits of prenatal co-supplementation strategies to improve neurobehavioral outcomes in offspring. Further studies are recommended to confirm these findings and explore underlying mechanisms.

Exploring the relationship between child temperament, maternal psychiatric symptoms, family environment and infant feeding

OBJECTIVES

Infant temperament is assumed to be primarily innate. However, newer research suggests that maternal affection impacts ratings of temperament and environmental factors, including feeding method, can also influence infant temperament. This study investigates child temperament and its relationships with maternal psychiatric symptoms, environmental variables and feeding method longitudinally in a cohort of children followed from 6 to 72 months. Differences in temperament by feeding group are also investigated. We hypothesized that maternal psychiatric symptoms, environmental stressors, and impaired family dynamics would have negative impact on child temperament, whereas breastfeeding would have a positive impact on child temperament.

METHOD

Mothers' ratings of child's temperament, own psychiatric symptomatology, environmental stresses and family cohesion were obtained in 504 mother-infant dyads via rating scales completed by mothers. Infants were breastfeed (BF), fed soy-based infant formula (SF) or dairy-based infant formula (MF). Linear mixed effect models investigated the relationship of variables on child's temperament while controlling for significant covariates and repeated measurements.

RESULTS

Mothers in this study did not endorse clinical-level psychiatric symptomatology; however, when adjusted for significant covariates, higher psychiatric symptomatology significantly correlated with environmental stressors, impaired family dynamics and elevations in temperament ratings of infants' adaptability and mood. There were no lasting differences for temperament between feeding groups. However, some significant transient increases in rhythmicity and adaptability were found between SF and BF children.

CONCLUSION

Positive relationships between family environment stressors and maternal psychiatric ratings were found. Transient differences were found in child temperament based upon feeding method.

Temperament in Early Childhood Is Associated With Gut Microbiota Composition and Diversity

Temperament is a key predictor of human mental health and cognitive and emotional development. Although human fear behavior is reportedly associated with gut microbiome in infancy, infant gut microbiota changes dramatically during the first 5 years, when the diversity and composition of gut microbiome are established. This period is crucial for the development of the prefrontal cortex, which is involved in emotion regulation. Therefore, this study investigated the relationship between temperament and gut microbiota in 284 preschool children aged 3-4 years. Child temperament was assessed by maternal reports of the Children's Behavior Questionnaire. Gut microbiota (alpha/beta diversity and genera abundance) was evaluated using 16S rRNA sequencing of stool samples. A low abundance of anti-inflammatory bacteria (e.g., Faecalibacterium) and a high abundance of pro-inflammatory bacteria (e.g., Eggerthella, Flavonifractor) were associated with higher negative emotionality and stress response (i.e., negative affectivity, β = -0.17, p = 0.004) and lower positive emotionality and reward-seeking (i.e., surgency/extraversion, β = 0.15, p = 0.013). Additionally, gut microbiota diversity was associated with speed of response initiation (i.e., impulsivity, a specific aspect of surgency/extraversion, β = 0.16, p = 0.008). This study provides insight into the biological mechanisms of temperament and takes important steps toward identifying predictive markers of psychological/emotional risk.

Effects of early-life gut microbiota on the neurodevelopmental outcomes of preterm infants: a multi-center, longitudinal observational study in China

To prospectively investigate associations between the features of gut microbiota at the fourth week after birth in preterm infants and neurodevelopment from 1 month of corrected age to 6 months of corrected age (MCA). Seventy-seven preterm infants were recruited from three NICUs of three tertiary hospitals between Apr 2021 to Sep 2022. Stool samples were collected during the fourth week after birth. Illumina MiSeq high-throughput sequencing technology was used to detect the composition and diversity of gut microbiota. Neurodevelopment assessments of preterm infants were conducted at 1, 3, and 6 MCA using the Ages and Stages Questionnaire, the third edition (ASQ-3). Spearman correlation, a generalized linear mixed model (GLMM), and permutational multivariate analysis of variance (PERMANOVA) analysis were used to horizontally and prospectively explore the associations between gut microbial and ASQ-3 dimension scores at each time point. The GLMM showed no significant associations between the alpha diversity and neurodevelopmental trajectory from 1 to 6 MCA. The beta diversity was significantly associated with gross motor scores at 1, 3, and 6 MCA (R2 = 0.067, p = 0.001; R2 = 0.039, p = 0.020; R2 = 0.031, p = 0.047); communication scores at 3 MCA (R2 = 0.030, p = 0.040); and fine motor scores at 6 MCA (R2 = 0.035, p = 0.022). After adjusting for covariates, the GLMM showed that the relative abundance of Klebsiella was negatively associated with gross motor score trajectory from 1 to 6 MCA (β =  - 1.449; 95% CI, - 2.275 to - 0.572; p = 0.001), while the relative abundance of Lactobacillus displayed a positive association (β = 1.421; 95% CI, 0.139 to 2.702; p = 0.030). Moreover, the relative abundance of Streptococcus was negatively associated with fine motor trajectory from 1 to 6 MCA (β =  - 1.669; 95% CI, - 3.305 to - 0.033; p = 0.046).

CONCLUSION

Our results suggest a possible association between the neonatal gut microbial diversity; the relative abundance of Klebsiella, Streptococcus, and Lactobacillus; and neurodevelopment from 1 to 6 MCA. In the future, clinical staff can focus on the window period of gut microbiota colonization, and implement probiotics targeted at the dominant genera to improve the neurodevelopment of preterm infants.

WHAT IS KNOWN

• In the fields of biology and medicine, current studies suggest that gut microbiota may play an important role in the critical window period of neurodevelopment through the gut-brain axis pathway. • Extensive preclinical research has implied the vital role of the initial gut colonization in the long-term neurodevelopment of children.

WHAT IS NEW

• The early-life gut microbiota was associated with neurodevelopment in preterm infants within 6 months of corrected age (MCA).

Psychobiotics and the Microbiota-Gut-Brain Axis: Where Do We Go from Here?

The bidirectional relationship between the gut microbiota and the nervous system is known as the microbiota-gut-brain axis (MGBA). The MGBA controls the complex interactions between the brain, the enteric nervous system, the gut-associated immune system, and the enteric neuroendocrine systems, regulating key physiological functions such as the immune response, sleep, emotions and mood, food intake, and intestinal functions. Psychobiotics are considered tools with the potential to modulate the MGBA through preventive, adjunctive, or curative approaches, but their specific mechanisms of action on many aspects of health are yet to be characterized. This narrative review and perspectives article highlights the key paradigms needing attention as the scope of potential probiotics applications in human health increases, with a growing body of evidence supporting their systemic beneficial effects. However, there are many limitations to overcome before establishing the extent to which we can incorporate probiotics in the management of neuropsychiatric disorders. Although this article uses the term probiotics in a general manner, it remains important to study probiotics at the strain level in most cases.

Bacterial community analysis identifies Klebsiella pneumoniae as a native symbiotic bacterium in the newborn Protobothrops mucrosquamatus

BACKGROUND

The study of the native microbiome of organisms is crucial. The connection between the native microbiome and the host affects the formation of the innate immune system and the organism's growth. However, the native microbiome of newborn venomous snakes has not been reported. Therefore, we aimed to determine the oral and skin microbiomes of newborn Protobothrops mucrosquamatus.

RESULTS

We performed 16 S full-length sequencing on 14 samples collected from 7 newborn P. mucrosquamatus individuals, specifically targeting their oral and skin microbiomes. In terms of the oral and skin microbiome, the main species were Klebsiella pneumoniae lineages. According to subspecies/species analysis, the proportion from highest to lowest was K. quasipneumoniae subsp. similipneumoniae, K. pneumoniae subsp. pneumoniae, and K. pneumoniae subsp. rhinoscleromatis. These three bacteria accounted for 62.5% and 85% of the skin and oral activity, respectively. The oral microbiome of newborn P. mucrosquamatus did not comprise common bacteria found in snakebite wounds or oral cultures in adult snakes. Therefore, the source of other microbiomes in the oral cavities of adult snakes may be the environment or prey. Functional Annotation of the Prokaryotic Taxa analysis showed that the skin/oral native microbiome metabolism was related to fermentation and human infection owing to the dominance of K. pneumoniae lineages. The characteristics of K. pneumoniae may impact the development of venom in venomous snakes.

CONCLUSION

The results of the native microbiome in the oral cavity and skin of newborn P. mucrosquamatus demonstrated that the habitat environment and prey capture may affect the composition of bacteria in adult snakes. We hypothesized that the native microbiome influences newborn venomous snakes and that K. pneumoniae lineages related to citrate fermentation may play a role in venom growth. However, further verification of this is required.