The Gut Microbiota's Role in Neurological, Psychiatric, and Neurodevelopmental Disorders

Abstract

Aim: This article aims to explore the role of the human gut microbiota (GM) in the pathogenesis of neurological, psychiatric, and neurodevelopmental disorders, highlighting its influence on health and disease, and investigating potential therapeutic strategies targeting GM modulation.

Materials and methods: A comprehensive analysis of the gut microbiota's composition and its interaction with the human body, particularly, its role in neurological and psychiatric conditions, is provided. The review discusses factors influencing GM composition, including birth mode, breastfeeding, diet, medications, and geography. Additionally, it examines the GM's functions, such as nutrient absorption, immune regulation, and pathogen defense, alongside its interactions with the nervous system through the gut-brain axis, neurotransmitters, and short-chain fatty acids (SCFAs).

Results: Alterations in the GM are linked to various disorders, including Parkinson's disease, multiple sclerosis, depression, schizophrenia, ADHD, and autism. The GM influences cognitive functions, stress responses, and mood regulation. Antibiotic use disrupts GM diversity, increasing the risk of metabolic disorders, obesity, and allergic diseases. Emerging therapies such as probiotics, prebiotics, and microbiota transplantation show promise in modulating the GM and alleviating symptoms of neurological and psychiatric conditions.

Conclusions: The modulation of the GM represents a promising approach for personalized treatment strategies. Further research is needed to better understand the underlying mechanisms and to develop targeted therapies aimed at restoring GM balance for improved clinical outcomes.

Keywords: autism; gut microbiota (GM); gut–brain axis; neuroinflammation; neurological disorders; probiotics.

Figure 1

The main taxa found during childhood. These taxa and some of their species are implicated in neurological and psychiatric diseases due to their increased population in the microbiota, such as Actinomycetota (Bifidobacterium spp.), Verrucomicrobia (Akkermansia spp.), Bacillota (Faecalibacterium spp.), Bacteroidota (such as Prevotella spp.), and Fusobacteriota (such as Fusobacterium spp.). Credits: Original figure by I.A. Charitos.

Figure 2

The main bacteria at level of families found during childhood in the gut microbiota. Several species from these families have a connection with neurological and psychiatric diseases or disorders such as Bacteroides spp., Doria spp., Bifidobacteria spp., Prevotella spp. and others.

Figure 3

The main genera found in pediatric population.

Figure 4

The three enterotypes are recognized based on the predominant bacterium: (1) Bacteroides, (2) Prevotella, and (3) Ruminococcus. In the first intestinal type, Slackia, Parabacteroides, Clostridiales, Alkaliphilus, Lactobacillus, Catenibacterium, and Geobacter coexist. Eggerthella, Veillonella, Ruminococcaceae, Holdemania, Peptostreptococcaceae, Staphylococcus, Leuconostoc, Desulfovibrionaceae, Rhodospirillum, Helicobacter, Escherichia, Shigella, and Akkermansia muciniphila also occur in the second intestinal type. Credits: Original figure by I.A. Charitos The third enteric type also includes Gordonibacter, Sphingobacterium, Staphylococcus, Marvinbryantia, Symbiobacterium, Dialister, and Akkermansia muciniphila. Credits: Original figure by I.A. Charitos.

Figure 5

The figure describes the hypotheses of how gut dysbiosis, due to emotional or stressful causes or not, can influence the bidirectional communication of the GBA, causing direct and indirect effects on the ENS and vice versa. Credits: Original figure by I.A. Charitos.