Abstract
- Background
Probiotics have been proposed to ameliorate cognitive impairment and depressive disorder via the gut–brain axis in patients and experimental animal models. However, the beneficial role of probiotics in brain functions of healthy older adults remains unclear. Therefore, a randomized, double-blind, and placebo-controlled multicenter trial was conducted to determine the effects of probiotics on cognition and mood in community-dwelling older adults.
- Methods
Sixty-three healthy elders aged 65 years or older consumed either a placebo or probiotics containing Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI for 12 weeks. The gut microbiota was analyzed using 16S rRNA sequencing and bioinformatics. Brain functions were measured using standardized neuropsychological tools including the Consortium to Establish a Registry for Alzheimer’s disease, Satisfaction with life scale, stress questionnaire, Geriatric depression scale, and Positive affect and negative affect schedule. Blood brain-derived neurotrophic factor levels were determined using an enzyme-linked immunosorbent assay.
- Results
The relative abundance of inflammation-causing gut bacteria was significantly reduced at Week 12 in the probiotics group compared to controls. The probiotics group showed greater improvement in the mental flexibility test and stress scores than the placebo group. Contrary to the placebo group, probiotics significantly increased serum brain-derived neurotrophic factor levels. Notably, gut microbes significantly shifted by probiotics, specifically Eubacterium and Clostridiales, showed a significant negative correlation with serum brain-derived neurotrophic factor levels only in the probiotics group.
- Conclusions
Probiotics promote mental flexibility and alleviate stress in healthy older adults, along with causing beneficial changes in the gut microbiota. These results provide clinical evidence supporting the health-promoting properties of probiotics as part of a healthy diet in older populations.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7861012/