Abstract

Objective: Cognitive impairment and dementia are prevalent and costly diseases, affecting 5-8 % of individuals aged 60 and above globally. Bifidobacterium, a low-cost probiotic, has shown potential in treating dementia, but its efficacy remains controversial. To investigate the effects of Bifidobacterium on various dementia-related functional tests and biomarkers in different patient populations with cognitive impairment and dementia.

Methods: Systematic searches were conducted on February 15, 2025, across Embase, PubMed, Medline, Wanfang, and ClinicalTrials.gov. The risk of bias was assessed using NOS. The study is registered with PROSPERO (CRD42023460809).

Results: After rigorous screening, 18 studies encompassing 1195 patients were included. The results revealed that Bifidobacterium significantly improved cognitive function (MMSE, WMD = 2.26, 95 % CI = 1.69-2.83, compared to placebo: p = 0.049), particularly in patients under 70 (MMSE, WMD = 2.81, 95 % CI = 1.97-3.65). For patients over 70, better outcomes were achieved without B. breve-based treatments (MMSE, WMD = 2.43, 95 % CI = 1.76-3.09, compared to the group age under 70 or the group over 70 and receiving B. breve-based treatments: p = 0.0133). Additionally, Bifidobacterium significantly enhance patients' memory, language, visuospatial, attention and executive abilities, potentially through the downregulation of triglycerides (WMD = -19.52, 95 % CI = -32.28 to -6.66, p = 0.039) and MDA (SMD = -0.72, 95 % CI = -1.07 to -0.37, p = 0.0057).

Conclusions: These findings provide key insights into the efficacy of Bifidobacterium, supporting personalized treatment strategies and reducing the treatment burden for patients with cognitive impairment and dementia.