Analyzing the therapeutic and preventive potential of probiotics in Alzheimer’s disease: a scoping review

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, neuroinflammation, and accumulation of amyloid-beta plaques and tau tangles. Emerging research emphasizes the gut-brain axis as a key modulator of AD pathogenesis, with gut microbiota influencing neuroimmune, neurochemical, and metabolic pathways. This review examines the therapeutic and preventive potential of probiotics, live beneficial microorganisms, in modulating the gut-brain axis to mitigate AD progression. Modifying gut microbiota presents a novel, potentially modifiable approach to influence AD pathophysiology and improve cognitive outcomes, offering insights for adjunctive clinical strategies. A systematic literature search was conducted across PubMed, Scopus, Web of Science, Google Scholar, and Cochrane Library for studies published up to July 2025. Studies were classified by design, sample size, follow-up duration, cognitive and biomarker outcomes, and risk of bias, following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines to ensure transparency and reproducibility. Preclinical studies indicate that probiotics can regulate gut microbiota, reduce oxidative stress, suppress neuroinflammation, and enhance synaptic plasticity, improving cognition in animal models. Clinical trials suggest potential benefits in humans, including improved memory scores and reduced inflammatory biomarkers, though limited sample sizes, trial duration, and strain variability constrain conclusions. Overall, probiotics demonstrate promise as an adjunctive intervention in AD. Further long-term, strain-specific, and large-scale clinical studies are needed to confirm efficacy, establish causality, and optimize therapeutic strategies.