Anti‐inflammation as one of the mechanisms in the improvement of cognitive function by probiotic Bifidobacterium breve strain

Abstract Background Recently, the gut‐brain axis has received a lot of attention as some probiotics have been reported to have a beneficial effect on CNS diseases. Our previous studies show that the probiotic strain, Bifidobacterium breve MCC1274 (synonym B. breve A1), improves memory scores in Alzheimer’s disease model and human subjects with self‐reported memory complaints. Furthermore, in a trial with healthy adults with MCI (Mild Cognitive Impairment), we found that B. breve MCC1274 significantly improved the cognitive function [1]. In the present study, we investigated the association of blood parameters with the improvement of cognitive function by B. breve MCC1274. Method In a double blind, randomized placebo‐controlled trial, healthy adults aged 50‐79 years with MCI consumed probiotic capsules (2x10 10 CFU/day) or placebo capsules for 16 weeks. Cognitive function was measured before and after the intervention using RBANS (Repeatable Battery for the Assessment of Neuropsychological Status) and JMCIS (Japanese version of MCI Screen) as neuropsychological tests. Hematological and biological blood parameters were measured to assess the safety and elucidate the possible action mechanism. Result Out of 80 participants, 79 subjects completed the study and after 16 weeks intervention, RBANS total score was significantly improved in the probiotic group in particular with significant improvement in domain scores of immediate memory, visuospatial/constructional, and delayed memory. Hematological and biological blood parameters showed no significant differences between the two groups. Interestingly, however, a significant correlation was found between the changes in blood HbA1c and RBANS total score in B. breve MCC1274 group (ρ=‐0.4218, p=0.0067). A stratified analysis based on baseline HbA1c with a median value (5.4%) showed a more remarkable benefit on the cognitive function by the probiotic consumption in the higher median subgroup (Fig 1). As many studies have reported an association between HbA1c and inflammation‐related dementia, this data suggests the mechanism of action of the probiotics may involve reducing inflammation. Conclusion The present data shows that B. breve MCC1274 improves cognitive function by reducing inflammation in healthy adults with MCI and may be a potential strategy for preventing dementia. Reference: (1) Xiao et al. Journal of Alzheimer’s Disease, 2020.