Mechanism of Exercise-Regulated Intestinal Flora for Alzheimer's Disease Based on Gut-Brain Axis

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive loss of cognitive function. Its main pathological features include accumulation of Amyloid-beta (Aβ) plaques, excessive phosphorylation of microtubule-associated protein tau (tau protein), and neuroinflammation. In recent years, studies have confirmed intestinal flora is closely connected to AD. Gut-brain axis has an important part in AD. Intestinal flora can achieve signal communication between gut and brain through metabolic, immune, neural, and endocrine pathways, thereby slowing down AD. It has been discovered that exercise is not only beneficial to physical health but also has a positive impact on the brain function. In recent years, more and more studies have found exercise can alleviate AD through the following four major pathways: regulating the diversity of intestinal flora, strengthening the blood-brain barrier (BBB), regulating immune homeostasis, and upregulating the brain-derived neurotrophic factor (BDNF). In this review, we have summarized intestinal flora in AD and systematically expounded potential regulatory pathways of exercise in modulating intestinal flora for AD. This provides a more theoretical basis for subsequent research targeting "gut-brain axis" to regulate AD. At the same time, this review also summarizes differences in different exercise types on improving intestinal flora for alleviating AD, providing new ideas and strategies for AD.