Olfactory impairment is the most common clinical manifestation among the elderly, and its prevalence increases sharply with age. Notably, growing evidence has shown that olfactory dysfunction is the first sign of neurodegeneration, indicating the importance of olfactory assessment as an early marker in the diagnosis of neurological disorders. In this review, we describe the nature of olfactory dysfunction and the advantage of using animal models in olfaction study, and we include a brief introduction to olfactory behavior tests widely used in this field. The contribution of microglia in the neurodegenerative processes including olfactory impairment is then discussed to provide a comprehensive description of the physiopathological role of interactions between neurons and microglia within the olfactory system.
Keywords: Niemann-Pick disease type C; microglia; neurodegenerative diseases; smell.