Probiotic Supplementation in Patients with Alzheimer's Dementia - An Explorative Intervention Study

Background: Dysbiosis of intestinal microbiota in the elderly can cause a leaky gut, which may result in silent systemic inflammation and promote neuroinflammation - a relevant pathomechanism in the early course of Alzheimer's disease. Objective: The rebalancing of the microbiome could benefically impact on gut inflammation and immune activation. Methods: In this study, routine laboratory tests in twenty outpatients (9 females, 11 males, aged 76.7 +/- 9.6 years) with Alzheimer's disease were investigated. The mean Mini Mental State Examination score was 18.5 +/- 7.7. Biomarkers of immune activation - serum neopterin and tryptophan breakdown - as well as gut inflammation markers and microbiota composition in fecal specimens were analyzed in 18 patients before and after probiotic supplementation for 4 weeks. Results: After treatment a decline of fecal zonulin concentrations and an increase in Faecalibacterium prausnitzii compared to baseline were observed. At the same time, serum kynurenine concentrations increased (p <0.05). Delta values (before - after) of neopterin and the kynurenine to tryptophan ratios (Kyn/Trp) correlated significantly (p <0.05). Conclusion: Results show that the supplementation of Alzheimer's disease patients with a multispecies probiotic influences gut bacteria composition as well as tryptophan metabolism in serum. The correlation between Kyn/Trp and neopterin concentrations points to the activation of macrophages and/or dendritic cells. Further studies are warranted to dissect the potential consequences of Probiotic supplementation in the course of Alzheimer's disease.