Abstract
The study of extracellular vesicles, particularly important in cancer research, is now attracting attention in psychiatry. In particular, exosomes, which are critical for intercellular communication, encapsulate a wide variety of biological substances. Brain‐derived exosomes can be extracted from peripheral blood, a process referred to as “brain liquid biopsy”, which is being widely discussed for its diagnostic potential in psychiatry. In autism spectrum disorders, activation of immune cells both inside and outside the brain has been reported, but the underlying pathophysiology remains unclear. This review explores the possibility that exosomes, due to their high permeability across the blood‐brain barrier, could affect immune cells inside and outside the brain, potentially triggering similar immune responses in both regions. The involvement of CNS‐associated macrophages, which are located in brain‐boundary areas more vulnerable to the blood‐brain barrier than in the brain parenchyma, is also discussed. These explanations underscore the potential of exosomes as a key player in the understanding and diagnosis of psychiatric disorders through their interaction with immune processes.
