A psychology of the human brain–gut–microbiome axis

Abstract

In recent years, we have seen increasing research within neuroscience and biopsychology on the interactions between the brain, the gastrointestinal tract, the bacteria within the gastrointestinal tract, and the bidirectional relationship between these systems: the brain–gut–microbiome axis. Although research has demonstrated that the gut microbiota can impact upon cognition and a variety of stress‐related behaviours, including those relevant to anxiety and depression, we still do not know how this occurs. A deeper understanding of how psychological development as well as social and cultural factors impact upon the brain–gut–microbiome axis will contextualise the role of the axis in humans and inform psychological interventions that improve health within the brain–gut–microbiome axis. Interventions ostensibly aimed at ameliorating disorders in one part of the brain–gut–microbiome axis (e.g., psychotherapy for depression) may nonetheless impact upon other parts of the axis (e.g., microbiome composition and function), and functional gastrointestinal disorders such as irritable bowel syndrome represent a disorder of the axis, rather than an isolated problem either of psychology or of gastrointestinal function. The discipline of psychology needs to be cognisant of these interactions and can help to inform the future research agenda in this emerging field of research. In this review, we outline the role psychology has to play in understanding the brain–gut–microbiome axis, with a focus on human psychology and the use of research in laboratory animals to model human psychology.

Gutsy Moves: The Amygdala as a Critical Node in Microbiota to Brain Signaling

“…In particular, a recent surge of interest in the gutbrain axis, and its regulation by the microbiome, has produced an ever-growing evidence base supporting the idea that the gut microbiota can alter both brain and behavior. [1][2][3][4][5] In this review, we will focus on the impact of the gut microbiota on the amygdala because this small, almondshaped brain region is a key regulator of many of the functions found to be altered by microbiota-gut-brain axis perturbations. While the investigation of the relationship between the microbiota and the amygdala is still relatively in its infancy, the early evidence suggests that both the structure and function of the amygdala can be influenced by the gut microbiota.…”

“…[1] Indeed, current evidence points to an influence of the gut microbiota in central nervous system (CNS) function, appropriate brain development, as well as psychological and behavioral outcomes. [1][2][3][4][5] There are many approaches available to chart the impact of the gut microbiome on CNS function albeit many are used much more in preclinical than human studies. [1,6] These include dietary manipulations, administration of specific strains of bacteria (e.g., probiotics), interventions which support the growth of beneficial bacteria (e.g., prebiotics), germ free (microbiota deficient) mice, antibiotic treatments, C-section delivery, and fecal microbiota transplants.…”

Bifidobacterium infantis 35624 and other probiotics in the management of irritable bowel syndrome. Strain specificity, symptoms, and mechanisms

“…At the very least, therefore, caution must be exercised in interpreting the conclusion of Yuan et al 5 that a specific probiotic strain will work better when combined with other probiotic strains. Not only did the combinations that they studied include different strains, but, as Yuan et al 5 and others 16 note, it is difficult to tease out what contribution(s) a single strain such as B. infantis 35624 provides when administered as a component of a probiotic cocktail containing multiple strains. More information is needed on interactions between different strains within probiotic cocktails-not just in the product, but also within the gut, and with constituents of the indigenous commensal microbiota.…”

The role of the brain–gut–microbiota axis in psychology: The importance of considering gut microbiota in the development, perpetuation, and treatment of psychological disorders

“…This paper adds to the burgeoning research into the brain–gut–microbiota axis (BGMA; Kelly, Clarke, Cryan, & Dinan, ) demonstrating that the discipline of psychology is on the cusp of a significant paradigm shift, moving away from CNS‐centric approaches toward a more holistic conceptualization of health and disease which integrates other body systems. We echo the sentiment of Allen, Dinan, Clarke, and Cryan () who call for a challenge to the reductionist approaches in psychology in favor of a multidisciplinary approach to conceptualizing and treating psychological disorders. In taking the unique approach of the Four P model of case formulation, this paper intends to review existing research on associations between GM and psychological outcomes, compiling it in a way that is more accessible to psychologists, especially those who have little previous knowledge regarding the BGMA.…”

“…Instead, it is to demonstrate the complex interconnectivity between multiple body systems in disease processes, from etiology through to treatment, and ideally prevention. In support of the call to action by Allen et al (), the discipline of psychology must shift away from its CNS‐centric conceptualization of disease and symptom‐centered disease treatment models toward a multidisciplinary approach to treatment and prevention. This paradigm shift will empower psychologists to better treat and care for their clients.…”