The interplay between gut microbiota and Alzheimer’s disease: mechanistic insights from dysbiosis to disease modulation
摘要
Alzheimer’s disease (AD) is a chronic, progressive, neurodegenerative condition marked by memory loss and cognitive decline. It is characterized by neuropathological features such as amyloid plaque accumulation, neurofibrillary tangles of tau protein, and inflammatory changes in the brain. Recent research emphasizes how gut microbes influence the onset and progression of AD primarily through the gut-brain connection, a bidirectional communication system. The human gastrointestinal tract (GI) contains trillions of bacteria, primarily Bacteroidetes, Firmicutes, and Actinobacteria, which play vital roles in digestion, metabolic regulation, and immune modulation. However, factors such as diet, lifestyle, and environmental exposure can disrupt microbial balance, weaken intestinal barrier function, and initiate systemic inflammation. Such dysbiosis has been linked to defective regulation of the amyloid precursor protein (APP), leading to increased deposition of amyloidogenic peptides (Aβ). Moreover, the enteric nervous system, which expresses APP, may serve as an initial site of amyloid deposition, affecting gastrointestinal motility and inflammatory susceptibility. The gut microbiota also produces key bioactive compounds, including neurotransmitters such as serotonin, dopamine, acetylcholine, histamine, and gamma-aminobutyric acid (GABA), which influence the central nervous system (CNS) through neural, immune, and endocrine pathways. An imbalance in these neuroactive molecules may disrupt synaptic signaling and contribute to Alzheimer’s-related cognitive dysfunction. Therefore, improving our understanding of gut-brain communication may advance knowledge of AD development and support the creation of new therapies. This review highlights the strong association between intestinal microbes and Alzheimer’s pathogenesis, emphasizing microbiota modulation through probiotics, prebiotics, postbiotics, synbiotics, and antibiotics as potential therapeutic approaches, supported by emerging clinical trial evidence.