Institute of Human Anatomy, Department of Neuroscience, University of Padova, Padova, Italy; Parkinson and Movement Disorders Unit, Department of Neuroscience, Centre for Rare Neurological Diseases (ERN-RND), University of Padova, Padova, Italy; Center for Neurodegenerative Disease Research (CESNE), University of Padova, Padova, Italy.
Parkinson and Movement Disorders Unit, Department of Neuroscience, Centre for Rare Neurological Diseases (ERN-RND), University of Padova, Padova, Italy; Center for Neurodegenerative Disease Research (CESNE), University of Padova, Padova, Italy.
Int Rev Neurobiol. 2022;165:91-102. doi: 10.1016/bs.irn.2022.08.001. Epub 2022 Sep 6.
Olfactory impairment is a common symptom in Coronavirus Disease 2019 (COVID-19), the disease caused by Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) infection. While other viruses, such as influenza viruses, may affect the ability to smell, loss of olfactory function is often smoother and associated to various degrees of nasal symptoms. In COVID-19, smell loss may appear also in absence of other symptoms, frequently with a sudden onset. However, despite great clinical interest in COVID-19 olfactory alterations, very little is known concerning the mechanisms underlying these phenomena. Moreover, olfactory dysfunction is observed in neurological conditions like Parkinson's disease (PD) and can precede motor onset by many years, suggesting that viral infections, like COVID-19, and regional inflammatory responses may trigger defective protein aggregation and subsequent neurodegeneration, potentially linking COVID-19 olfactory impairment to neurodegeneration. In the following chapter, we report the neurobiological and neuropathological underpinnings of olfactory impairments encountered in COVID-19 and discuss the implications of these findings in the context of neurodegenerative disorders, with particular regard to PD and alpha-synuclein pathology.
嗅觉障碍是由严重急性呼吸系统综合征冠状病毒 2（SARS-CoV-2）感染引起的 2019 年冠状病毒病（COVID-19）的一种常见症状。虽然其他病毒，如流感病毒，也可能影响嗅觉能力，但嗅觉功能的丧失通常更平稳，并且与各种程度的鼻部症状相关。在 COVID-19 中，嗅觉丧失可能在没有其他症状的情况下出现，通常突然发生。然而，尽管 COVID-19 嗅觉改变引起了极大的临床关注，但对于这些现象的潜在机制知之甚少。此外，嗅觉功能障碍在帕金森病（PD）等神经疾病中也有观察到，并且可能在运动发作前多年就出现，这表明病毒感染（如 COVID-19）和区域性炎症反应可能引发异常的蛋白质聚集和随后的神经退行性变，可能将 COVID-19 嗅觉障碍与神经退行性变联系起来。在接下来的章节中，我们报告了 COVID-19 中遇到的嗅觉障碍的神经生物学和神经病理学基础，并讨论了这些发现在神经退行性疾病背景下的意义，特别是在帕金森病和α-突触核蛋白病理学方面。
