Abstract: As the global population is aging, elderly individuals are increasingly facing significant health challenges, especially mental health issues such as emotional problems, sleep disturbance, and cognitive impairment. Probiotics, defined as live microorganisms that confer health benefits upon the host, have emerged as an effective means to improve the mental health of the elderly. Studies have shown that the gut microbiota regulates brain development and behavior in older adults through the gut-brain axis. This article focuses on summarizing the characteristics of the nervous system in the elderly and its connection to the gut microbiota, the characteristics of the gut microbiota in older individuals, and the mechanisms underlying the regulation of the nervous system in the elderly by the gut-brain axis. It also discusses recent advancements in understanding the role of probiotics in improving mental health conditions of the elderly, such as mild cognitive impairment, insomnia, depression, and Alzheimer’s disease, with the aim of providing a theoretical basis for the clinical application of probiotics and the management of mental health in older adults.

Key words: gut-brain axis; older adults; mental disorders; probiotics; research progress