The impact of supplements on cognitive function for Alzheimer's disease or mild cognitive impairment: a systematic review and network meta-analysis

OBJECTIVE: Global aging is increasing the incidence of Alzheimer's disease (AD) and mild cognitive impairment (MCI). This network meta-analysis evaluates the effects of dietary supplements on cognitive function in AD/MCI patients. METHODS: We systematically searched PubMed, Embase, Cochrane Library, and Web of Science for randomized controlled trials up to July 2024. Study quality was assessed using risk-of-bias tools, and a network meta-analysis was performed using R and STATA. RESULTS: increased MMSE scores (MD = 1.02, 95% CI 0.41-1.63, intervention vs placebo). In comparisons where placebo was the reference group, the following supplements were superior: plant extraction (MD = -1.54, 95% CI -1.88 to -1.19), probiotics with selenium (MD = -1.7, 95% CI -2.34 to -1.05), phosphatidylserine-100 mg (MD = -1.14, 95% CI -1.86 to -0.41), spirulina (MD = -0.68, 95% CI -1.23 to -0.13), and vitamin B (MD = -0.88, 95% CI -1.67 to -0.09). Probiotics with selenium showed the strongest effect. No supplement produced significant improvements on the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog). CONCLUSION: , probiotic-selenium combinations, and plant extracts, are associated with improvements in MMSE scores among AD/MCI patients. The absence of effects on ADAS-Cog scores underscores the importance of assessment tool selection. This study provides evidence for considering nutritional interventions in cognitive support strategies.