Plain language summary
The gut microbiome and brain communicate through various pathways via the gut-brain axis. While this relationship is becoming more established, no current studies have demonstrated whether cognitive decline or cognitive stimulation directly impact the makeup of the gut microbiome. The aim of this study was to assess the efficacy of cognitive stimulation through a mindfulness practice in modulating the gut microbiome in patients experiencing mild cognitive impairment (MCI). In this study, 123 elderly individuals were given cognitive function tests and classified as either Normal Aging or MCI, and their gut microbiota profiles were assessed to establish baseline data between the two groups. Half of the MCI patients were randomly assigned to participate in a weekly mindfulness program for three months, and then monthly for six months, and stool and blood samples were collected at baseline, three months, and nine months. This study found an alteration in cognitive capacity led to the changes in specific microbiota in elderly adults diagnosed with MCI. Based on these results, the authors highlight the brain to gut microbiota communication pathway and propose the gut microbiome be considered as a risk factor of MCI.
Abstract
There is ample scientific and clinical evidence of the effects of gut microbiota on the brain but no definitive evidence that the brain can affect changes in gut microbiota under the bi-directional gut-brain axis concept. As there is no pharmacotherapeutic intervention for the early stages of cognitive decline, research has focused on cognitive stimulation in reversing or slowing the impairment. Elderly patients diagnosed with mild cognitive impairment underwent a randomized-control trial of mindful awareness practice. Neuropsychological assessments, inflammatory markers, and gut microbiota profiles were tested. Here, we report that their cognitive impairment was improved and associated with changes in gut bacterial profile. A cognition-score-dependent-abundance was observed in Ruminococcus vs Recognition Trials (RT), Digit Span Backward (DSB), Semantic Fluency Span (SFS) and Memory Domain (MD); Coprococcus vs DSB, Color Trails Test 2 (CTT2) and Block Design (BD); Parabacteroides vs DSB and SFS; Fusobacterium vs DSB and CTT2; Enterobacteriaceae vs BD and SFS; Ruminococcaceae vs DSB; Phascolarctobacterium vs MD. The study showed for the first-time, alteration in the cognitive capacity leading to the corresponding changes in microbiota profiles. This strongly suggests that signals from the different segments of brain could dictate directly or indirectly the abundances of specific gut microbes.
Methodological quality
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