Effects of probiotics on cognitive and emotional functions in healthy older adults: Protocol for a double-blind randomized placebo-controlled crossover trial

Cognitive and Emotional Effect of a Multi-species Probiotic Containing Lactobacillus rhamnosus and Bifidobacterium lactis in Healthy Older Adults: A Double-Blind Randomized Placebo-Controlled Crossover Trial

As the population ages, cognitive decline becomes more common. Strategies targeting the gut-brain axis using probiotics are emerging to achieve improvements in neuropsychiatric and neurological disorders. However, the beneficial role of probiotics on brain function in healthy older adults remains unclear. Our aim was to evaluate a multi-species probiotic formulation as a therapeutic approach to reduce emotional and cognitive decline associated with aging in healthy adults. A randomized double-blind placebo-controlled crossover trial was conducted. The study involved a 10-week intervention where participants consumed the assigned probiotic product daily, followed by a 4-week washout period before the second condition started. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and the Psychological Experiments Construction Language Test Battery. At the emotional level, the Beck Depression Inventory (BDI) and the State-Trait Anxiety Inventory (STAI) were used. Thirty-three participants, recruited between July 2020 and April 2022, ingested a multispecies probiotic (Lactobacillus rhamnosus and Bifidobacterium lactis). After the intervention, noticeable enhancements were observed in cognitive function (mean difference 1.90, 95% CI 1.09 to 2.70, p < 0.005), memory (mean difference 4.60, 95% CI 2.91 to 6.29, p < 0.005) by MMSE and digit task, and depressive symptoms (mean difference 4.09, 95% CI 1.70 to 6.48, p < 0.005) by BDI. Furthermore, there were significant improvements observed in planning and problem-solving skills, selective attention, cognitive flexibility, impulsivity, and inhibitory ability. Probiotics administration improved cognitive and emotional function in older adults. Limited research supports this, requiring more scientific evidence for probiotics as an effective therapy for cognitive decline. This study has been prospectively registered at ClinicalTrials.gov (NCT04828421; 2020/July/17).

Effects of human probiotics on memory and psychological and physical measures in community-dwelling older adults with normal and mildly impaired cognition: results of a bi-center, double-blind, randomized, and placebo-controlled clinical trial (CleverAge biota)

Objectives

This study presents results of our randomized clinical trial studying the effect of human probiotics on memory and psychological and physical measures following our study protocol registered at clinicaltrials.gov NCT05051501 and described in detail in our previous paper.

Methods

Community dwelling participants aged between 55 and 80  years were randomly assigned to receive a single dose of 10⁶ colony-forming units of human Streptococcus thermophilus GH, Streptococcus salivarius GH NEXARS, Lactobacilus plantarum GH, and Pediococcus pentosaceus GH or placebo. A cross-over design allowed each group to receive probiotics and placebo for 3  months each in reverse order. A small subset of participants was examined online due to the COVID-19 pandemic. After 6  months a small number of volunteers were additionally assessed after 2  months without any intervention. Primary outcome measures included changes in cognitive functions assessed using brief tests and a neuropsychological battery and changes in mood assessed using validated questionnaires. Secondary outcome measures included changes in self-report and subjective measures using depression and anxiety questionnaires, seven visual analog scales of subjective feelings (memory, digestion, etc.), and physical performance.

Results

At baseline, the probiotic-placebo group A (n = 40, age 69 ± 7 years, education 16 ± 3 years, 63% females, body mass index 28.5 ± 6, subjective memory complaint in 43%) did not differ from the placebo-probiotic group B (n = 32) in any of the sociodemographic characteristics and evaluated measures including cognitive status. At follow-up visits after 3, 6, and 8  months, no cross-sectional differences in any of the measures were found between the groups except worse sentence recall of the ALBA test after 3  months of probiotic use. Score changes were not observed for all cognitive tests but one in any group between visits 1 and 3 and between visits 3 and 6. The only change was observed for the TMT B test after the first three months but no change was observed after the second three months.

Conclusion

The treatment with human probiotics and prebiotics did not improve cognitive, affective, or physical measures in community-dwelling individuals with normal or mildly impaired cognitive functions.

Clinical trial registration

clinicaltrials.gov, identifier NCT05051501.

Ginsenoside Rb1 improves intestinal aging via regulating the expression of sirtuins in the intestinal epithelium and modulating the gut microbiota of mice

Intestinal aging seriously affects the absorption of nutrients of the aged people. Ginsenoside Rb1 (GRb1) which has multiple functions on treating gastrointestinal disorders is one of the important ingredients from Ginseng, the famous herb in tradition Chinese medicine. However, it is still unclear if GRb1 could improve intestinal aging. To investigate the function and mechanism of GRb1 on improving intestinal aging, GRb1 was administrated to 104-week-old C57BL/6 mice for 6 weeks. The jejunum, colon and feces were collected for morphology, histology, gene expression and gut microbiota tests using H&E staining, X-gal staining, qPCR, Western blot, immunofluorescence staining, and 16S rDNA sequencing technologies. The numbers of cells reduced and the accumulation of senescent cells increased in the intestinal crypts of old mice, and administration of GRb1 could reverse them. The protein levels of CLDN 2, 3, 7, and 15 were all decreased in the jejunum of old mice, and administration of GRb1 could significantly increase them. The expression levels of Tert, Lgr5, mKi67, and c-Myc were all significantly reduced in the small intestines of old mice, and GRb1 significantly increased them at transcriptional or posttranscriptional levels. The protein levels of SIRT1, SIRT3, and SIRT6 were all reduced in the jejunum of old mice, and GRb1 could increase the protein levels of them. The 16S rDNA sequencing results demonstrated the dysbiosis of the gut microbiota of old mice, and GRb1 changed the composition and functions of the gut microbiota in the old mice. In conclusion, GRb1 could improve the intestinal aging via regulating the expression of Sirtuins family and modulating the gut microbiota in the aged mice.