Annual Research Review: Critical windows - the microbiota-gut-brain axis in neurocognitive development

Nested sensitive periods: how plasticity across the microbiota-gut-brain axis interacts to affect the development of learning and memory

There is a growing appreciation for the range of sensitive periods which occur across the brain. These sensitive periods give rise to sensory outcomes, as well as complex higher-order cognitive functions like learning and memory. More recently, an understanding that sensitive periods of development occur outside of the central nervous system (e.g., in the gastrointestinal microbiota) has emerged. Less well understood is how these peripheral sensitive periods may interact with those operating centrally to influence complex behavior. The goal of this paper is to put forward the view that sensitive periods of development occur across the entirety of the microbiota-gut-brain (MGB) axis, and that these nested sensitive periods may interact to influence learning and memory outcomes. Adopting this framework should promote a 'new wave' of thinking in the field which appreciates the complex central and peripheral forces acting on behavior, and uses that understanding to innovate therapies and interventions for disordered learning and memory systems.

Food Insecurity, Malnutrition, and the Microbiome

Purpose of Review

Food insecurity is defined as the disruption of food intake or eating patterns because of lack of money and other resources. Although a relationship between food insecurity and malnutrition would seem intuitive, this relationship remains unclear. This review was aimed at summarizing the emerging evidence of the relationship between food insecurity, malnutrition, and intestinal microbial changes.

Recent Findings

Evidence suggests that malnutrition is certainly associated with alteration in the intestinal microbiome. Alternative theories have been proposed as to the nature of the alteration, whether that be a result of microbial immaturity, dysbiosis, or contributions from both processes.

Summary

Although the evidence continues to evolve, targeted nutritional therapies in conjunction with specific microbial therapy of probiotics or prebiotics may hold great promise for the treatment of malnutrition in the clinical and community settings.

Early Life Stress and the Development of the Infant Gut Microbiota: Implications for Mental Health and Neurocognitive Development

PURPOSE OF REVIEW

We review the state of the literature examining associations between early life stress (ELS), gut microbiota, and neurocognitive development and mental health in animals and humans. We identify gaps in current models and areas for future research.

RECENT FINDINGS

ELS is associated with changes in gut microbiota, which correspond to changes in affective and cognitive functioning in both animals and humans. Some of these ELS-induced psychological changes can be remedied by supplementation with probiotics in early life, suggesting a potential area for intervention for ELS-exposed children. Prenatal stress exposure is rarely studied in humans in relation to gut microbiota, but animal work has suggested important associations between prenatal stress and fetal programming that should be tested in humans. The gut microbiota plays an important role in the association between ELS, neurocognitive development, and mental health. More work is needed to fully understand these associations in humans.

Commentary: Microbial panaceas: does development have the answer? - reflections on Cowan, Dinan, & Cryan (2020)

Is the microbiome a promising adjunct, a potential panacea, or a distraction from feasible treatments for neurodevelopmental disorders? Taking a developmental approach may get us closer to understanding the data and give us pause in trying to translate this nascent field to the clinic right now.