Effects of Bifidobacterium breve A1 on the cognitive function of older adults with memory complaints: a randomised, double-blind, placebo-controlled trial

Abstract

In our previous study, we reported the therapeutic potential of Bifidobacterium breve A1 in preventing cognitive impairment in a mouse model of Alzheimer’s disease and participants with mild cognitive impairment; we suggested that probiotic supplementation is an effective therapeutic strategy for managing cognitive function. Accordingly, we conducted a randomised, double-blind, placebo-controlled trial to assess whether 12-week B. breve A1 supplementation could affect the cognitive function of elderly subjects with memory complaints. We assessed cognitive function using the Japanese version of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and Mini-Mental State Examination (MMSE) at baseline and after 12 weeks of probiotic supplementation. A total of 121 participants were randomised and received B. breve A1 capsules or placebo daily for 12 weeks; of these, 117 participants completed the study. At 12 weeks, neuropsychological test scores significantly increased in both groups; no significant intergroup difference was observed in terms of changes in scores from the baseline scores. However, a stratified analysis revealed a significant difference between B. breve A1 and placebo groups in terms of the subscale ‘immediate memory’ of RBANS and MMSE total score in the subjects with low RBANS total score at baseline. No significant differences in terms of blood parameters between the groups or adverse effects caused by B. breve A1 intervention were observed. The results of the present study suggest the safety of B. breve A1 supplementation and its potential in maintaining cognitive function in elderly subjects with memory complaints. However, future large-scale studies on individuals with impaired cognitive function are required to validate the present findings.

Fecal Microbiota Transplantation in Neurological Disorders

“…Conversely, other studies suggested that microbiota depletion may negatively affect cognitive function and microglia and synaptic function in mice and contrasting results were also observed in humans (Laake and Oeksengaard, 2002;Angelucci et al, 2019). Furthermore, a positive effect of probiotics on cognitive function was observed in animal models and AD patients or adults with mild cognitive impairment (Davari et al, 2013;Jiang et al, 2017;Kobayashi et al, 2017Kobayashi et al, , 2019aRezaei Asl et al, 2019;Tamtaji et al, 2019), whereas one study reported no to little effect (Kobayashi et al, 2019b). Erny et al (2015) observed defects of microglia in germ-free mice leading to impaired innate immune responses.…”

Gut–Brain Axis: Role of Gut Microbiota on Neurological Disorders and How Probiotics/Prebiotics Beneficially Modulate Microbial and Immune Pathways to Improve Brain Functions

“…Probiotics plus selenium intake resulted in significant reduction in high sensitivity CRP, insulin, serum triglycerides, HOMA-IR, VLDL, and LDL levels and significant increase in total antioxidant capacity compared with only selenium and placebo [ 172 ]. In a randomized, double-blind, placebo-controlled study, 12 weeks of B. breve A1 supplementation improved cognitive function in elderly subjects with memory complaints [ 173 ]. In an open-label single-arm study, intake of the same strain B. breve A1 was significantly improved hospital anxiety and depression scale (HADS) score and Positive and Negative Syndrome Scale (PANSS) at four weeks [ 174 ].…”

Efficacy of probiotics on cognition, and biomarkers of inflammation and oxidative stress in adults with Alzheimer’s disease or mild cognitive impairment — a meta-analysis of randomized controlled trials

“…All studies were randomized, double-blind and controlled trials. Among which, three studies [27][28][29] recruited subjects diagnosed with AD and another two [30,31] included MCI adults. Most studies included a higher ratio of women except for two studies (one [30] had a balanced proportion and the other [28] did not report the sex ratio of the recruited subjects).…”

“…The intervention duration of the involved studies was all 12 weeks. Two studies [30,31] used a sole strain of probiotics, while the other three studies applied multiple strains. The study from Azadeh Agahi et al [29] had two active probiotics groups which were regarded as one group for the present analysis.…”

“…These preclinical results have indicated that probiotics might be an effective dietary intervention to ameliorate age-associated cognitive deficits. Nevertheless, findings from available clinical trials focusing on the effects of probiotics in patients with AD or MCI are inconsistent [27][28][29][30][31]. Additionally, the previous relevant reviews are focused on the effect of probiotics on neurodegenerative and neurodevelopmental disorders in both animal models and human trials.…”