Synbiotic Supplementation and Its Effects on Cognition in Alzheimer’s Patients: A Double-blind Study

Introduction: Dementia is a progressive neurodegenerative disorder and a significant healthcare concern increasing worldwide. The modulation of the gut-brain axis by gut microbiota might have favorable effects on ameliorating cognitive decline. We aimed to investigate whether synbiotics administration could enhance cognition and function in older adults with non-severe Alzheimer’s disease (AD).  Methods: This study was designed as a randomized, placebo-controlled, double-blind clinical trial to test the effects of synbiotic supplementation for 90 days (between August 2019 and February 2021). A synbiotics formulation or placebo was randomly allocated to older outpatients with mild to moderate AD. The intervention group took two capsules daily containing a mixture of 7 bacterial strains as probiotics and a prebiotic for 12 weeks. Mini-mental state examination (MMSE) and Barthel index evaluated participants’ cognition and functional status. Pre-intervention and post-intervention fasting blood samples were obtained to compare their serum albumin (Alb), fasting blood sugar (FBS), 25(OH) vitamin D, and lipid profile. Results: A total of 60 patients with a mean age of 77 years were recruited. After 12 weeks of synbiotic supplementation, no significant improvement was detected in the MMSE score (P=0.53) and Barthel index (P=0.43). Furthermore, metabolic parameters including FBS (P=0.92), triglyceride (P=0.48), total cholesterol (P=0.74), high-density lipoprotein (HDL) (P=0.54), low-density lipoprotein (LDL) (P=0.79), serum Alb (P=0.28) and 25(OH) vitamin D levels (P=0.67) were not different before and after synbiotic administration.  Conclusion: This study does not support the idea that short-term synbiotic supplementation could enhance cognitive and physical function in older patients with mild to moderate AD.