Evaluation of improvement of cognitive impairment in older adults with probiotic supplementation: A systematic review and meta-analysis.

OBJECTIVE: This study aimed to evaluate the improvement of cognitive impairment in older adults through probiotic supplementation. METHODS: A literature review on probiotic supplementation for treating cognitive impairment in older adults was conducted using English and Chinese databases from 1984 to 2023. Two researchers extracted relevant data independently, and a meta-analysis was performed with RevMan software. RESULTS: A comprehensive analysis of ten pertinent papers was conducted, involving a sample of 702 old adults with cognitive impairment. The findings from this study revealed that probiotic supplementation exhibited a positive impact on cognitive symptoms, specifically memory (MD = 0.14, 95% CI :0.05～0.22, P = 0.001) and overall cognitive function (SMD = 0.73, 95% CI: 0.25～1.21, P=0.003), as well as oxidative stress levels, including total antioxidant capacity (MD=52.54, 95% CI:39.52～65.56, P < 0.01), malondialdehyde (MD=-0.11, 95% CI:-0.15～-0.07, P < 0.01), and glutathione (MD=17.08, 95% CI:8.65～25.5, P < 0.01). However, probiotic supplementation failed to enhance patients' psychological symptoms (SMD =0.18, 95% CI:-0.56～0.92, P = 0.64). CONCLUSIONS: Probiotic supplementation can enhance cognitive symptoms and decrease oxidative stress in older adults with cognitive impairment. However, it does not improve psychological symptoms. More research is needed to determine the effects of probiotic supplementation on gastrointestinal symptoms and sleep quality in this population. Further supplementation and improvement will be necessary once high-quality literature becomes available.