Exosomes are a subtype of extracellular vesicles derived from endosomes and released by membrane fusion and exocytosis. Exosome-mediated intercellular communication plays a critical role in multiple physiological and pathological processes. Due to their low immunogenicity and ability to mediate long-distance transport of bioactive substances, exosomes are considered ideal biological carriers for drugs. Engineered exosomes can improve the targeting of drug delivery, making research on exosome-based drug delivery exceedingly promising. However, some studies have indicated that exosomes can facilitate pathological processes in diseased organisms. For instance, exosomes secreted by tumor cells can "mislead" immune cells or establish a favorable microenvironment, thus promoting tumor proliferation and migration. In neurodegenerative diseases, exosomes exacerbate the disease by promoting inflammatory responses and the spread of pathogenic proteins. This article reviews the development and pathological propagation of neurodegenerative diseases mediated by exosomes carrying toxic pathogenic proteins , offering new insights into the occurrence and development of neurodegenerative diseases, as well as cautions and recommendations for exosome engineering and clinical applications.