Olfactory dysfunction in Alzheimer's disease

Abstract

Alzheimer's disease (AD) is the most common neurodegenerative disease that causes dementia. Olfactory dysfunction is detected at preclinical stage of this disease, this is important for the early appointment of therapy. The smell identifcation process involves the olfactory and orbitofrontal cortex, mediobasal structures of the temporal region, including the entorhinal cortex and hippocampus, which makes it extremely sensitive to neurodegeneration, especially of the Alzheimer's type. In patients at risk of developing AD (for example, carriers of the APOE4 genotype), patients with mild cognitive impairment and subjective cognitive decline also have olfactory dysfunction, which increases with the progression of cognitive defcit. This article presents the proposed mechanisms of hyposmia development in patients with Alzheimer's disease, the main methods of its study, such as olfactory tests, evoked olfactory potential, MRI and functional MRI, as well as data from population studies of recent years.