The Girona Biomedical Research Institute (IDIBGI) has published a comprehensive review in the journal ‘Cell Host & Microbe’ that highlights the increasingly evident link between gut microbiota and human cognitive function. The paper not only analyses the mechanisms by which gut microorganisms can influence the brain, but also highlights the need for a more integrated and complex approach to understanding this microbiota-gut-brain axis, including other types of microbes beyond bacteria.
The gut microbiota is the set of microorganisms that inhabit our digestive tract, and plays an essential role in processes such as digestion, nutrient absorption, metabolism and regulation of the immune system. However, one of the most fascinating discoveries in recent years has been the identification of an axis linking the gut microbiota to the brain. Recent research has shown that this link influences such crucial aspects as social behaviour, cognitive function and the neurobiology of brain regions related to learning and memory.
In this review, IDIBGI and CIBERObn researchers Dr. José Manuel Fernández-Real, leader of the Nutrition, Eumetabolism and Health research group and head of the Endocrinology section at Hospital Trueta, Dr. Jordi Mayneris-Perxachs, leader of the Integrative Systems Medicine and Biology research group, and Dr. Anna Castells-Nobau, post-doctoral researcher in both groups, have conducted an exhaustive analysis of the existing research on this connection.
Under-studied populations in the gut microbiota
The review emphasises the need to expand research in this field to include other microbial populations, such as archaea, eukaryotes and especially viruses, which are often forgotten components of the microbiota. Although viruses, and especially viruses that infect bacteria, called bacteriophages, have a significant presence in the human gut microbiota, their role remains poorly understood. However, recent studies indicate that they may play a key role in modulating neuronal gene expression, opening up new avenues for future research.
One example is recent research led by the same authors published in the same journal, which reveals the association of a type of bacteriophage present in the gut microbiota, the Caudovirales, with improved cognitive ability in humans, mice and flies.
Another innovative aspect of the review is the proposal to apply a new multidisciplinary approach, called systems biology, to better understand the multilevel interactions (genes, proteins, metabolites, etc.) between the microbiota and cognition. This perspective analyses the biological system as an integrated whole, without forgetting that its parts also act autonomously.
Microbiota-based personalised medicine
The review also highlights the potential of the gut microbiota as a key modulator of cognitive function, suggesting that microbiota modification could be harnessed to develop personalised therapies to improve cognitive health. This could be particularly relevant for mitigating the symptoms of cognitive degeneration associated with ageing or in the treatment of neurodegenerative diseases such as Alzheimer's disease.
Thus, this work suggests that the high variability of microbiota composition between individuals opens the door to personalised medicine that takes into account both microbiota and genetics, thus paving the way towards new therapeutic approaches to improve cognitive health and, by extension, quality of life.
Reference article: Castells-Nobau A, Mayneris-Perxachs J, Fernández-Real JM. Unlocking the mind-gut connection: Impact of human microbiome on cognition. Cell Host Microbe. 2024 Aug 14;32(8):1248-1263. doi: 10.1016/j.chom.2024.07.019. PMID: 39146797.
