Non-dysbiotic gut microbiota profiles are associated with different spontaneous cortical activity in healthy older people

The gut and the brain have shown to be linked through a multimodal, bidirectional pathway called the gut-brain axis. In the gut-to-brain way, the gut microbiota has been shown to be the main factor. The physiological and biochemical mechanisms of this communication have been described in detail, and the gut microbiota has been shown to be altered in many neurological and psychiatric conditions. However, it is unknown how the gut microbiota influences the brain activity, especially in the healthy condition. By clustering healthy older people by their corresponding microbiome and comparing their spontaneous cortical activity, we demonstrate that different unaltered microbiota profiles are associated with different spontaneous activity in medial posterior cortical areas. These areas are associated to memory, language and emotion processing abilities. Therefore, we provide evidence that normal gut microbiota profiles modulate spontaneous cortical activity related to cognitive functions that typically decline with age. This implies that nutritional interventions that modify microbiota composition could help delay or ameliorate natural age-related cognitive decline.