en Clinical Neuroscience Clinical Neuroscience Original Original <div style="text-align: justify;"><strong>Introduction</strong>: 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&rsquo;s disease (AD).&nbsp;<br> <strong>Methods</strong>: 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&rsquo; 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.<br> <strong>Results</strong>: 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.&nbsp;<br> <strong>Conclusion</strong>: 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.&nbsp;</div> Synbiotics, Cognitive function, Activity of daily living, Elderly, Alzheimer’s disease (AD) 833 842 http://bcn.iums.ac.ir/browse.php?a_code=A-10-4648-1&slc_lang=en&sid=1 Mahdieh Mehmandoust mehmandoost_tums96@yahoo.com 13700319475328460051213 0009-0002-7144-674X No Department of Geriatric Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Shima Raeesi shraeesi@sina.tums.ac.ir 13700319475328460051214 13700319475328460051214 No Department of Geriatric Medicine, Ziaeian Hospital, Tehran University of Medical Sciences, Tehran, Iran. Rezvan Hashemi Rezvan.hme@gmail.com 13700319475328460051215 13700319475328460051215 No Department of Geriatric Medicine, Ziaeian Hospital, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Bidkhori bidkhorimohammad93@gmail.com 13700319475328460051216 13700319475328460051216 No Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Alireza Namazi Shabestari namazi@sina.tums.ac.ir 13700319475328460051217 13700319475328460051217 No Department of Geriatric Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Fatemeh Dashti Fatemehda1996@gmail.com 13700319475328460051218 13700319475328460051218 No Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Farzaneh Asoudeh a.asodeh75@gmail.com 13700319475328460051219 13700319475328460051219 No Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Zahra Vahabi zvahabi@sina.tums.ac.ir 13700319475328460051220 13700319475328460051220 Yes Department of Geriatric Medicine, Ziaeian Hospital, Tehran University of Medical Sciences, Tehran, Iran.