Neurological disorders and coronavirus 2019 (COVID-19) pandemic are two conditions with a recent well-documented association. Intriguing evidences showed that COVID-19 infection can modify clinical spectrum of manifested neurological disorders but also it plays a crucial role in the development of future diseases as long-tem consequences.
In this viewpoint review, we aimed to assess the vulnerability to SARS-CoV-2 infection and development of COVID-19 among neurological disorders. With this in mind, we tested the hypothesis that age rather than neuropathology itself could be decisive in neurodegenerative diseases such as Parkinson’s disease, whereas neuropathology rather than age may be critical in neuroimmunological diseases such as Multiple Sclerosis.
Highlighting the role of potential susceptibility or protection factors from this disastrous infection, we also stratify the risk for future neurodegeneration.
In this section, we will discuss the impact of SARS-CoV-2 viral infection for patients with neurodegenerative conditions with a magnifying glass on patients with movement disorders andCOVID-19 and Neurological Disorders dementias. Since SARS-CoV-2 effects on neurodegenerative, as well as neuroimmune diseases, might vary across the different pathogenesis and clinical features, we consider the evidence within three sections: (i) vulnerability to the infection; (ii) modification of the clinical course of disease, in relation to clinical neurological manifestations, disease progression and innovative strategies, to support clinicians in the management of the disease; (iii) trigger for future neurodegeneration.
There are at least two well-consolidated evidence linking COVID-19 to movement disorders, especially for PD. First, the presence of antibodies against coronavirus in the cerebrospinal fluid of patients with PD revealed more than 2 decades ago . Second, the ability of coronaviruses to enter the brain through the nasal cavity causing anosmia/hyposmia . The facts that hyposmia is a common premotor feature of PD and that olfactory bulb is a selective target of the deposition of alpha-synuclein pathology , might to be more than just a coincidence.
In the context of emerging COVID-19 pandemic, an urgent attention should be focused on a population of particular interest such as that neuroimmunological disorders. In this section, we will discuss the impact of the SARS-CoV-2 viral infection for patients with these conditions with a magnifying glass on patients with Multiple Sclerosis (MS). No consistent data are to date available for other neuroimmunological disorders such as neuromyelitis optica spectrum disorders, Guillain–Barré syndrome or chronic dysimmune neuropathies.
The most important clinical lesson we have learned from COVID-19 in neurological disorders is that COVID-19 is really a completely unpredictable condition. We found that PD neuropathology itself may be a protective factor against the SARS-CoV-2 infection, whereas age and progressive course of the disease are potential risk factors in MS disease.
Thus the final answer to our initial question is that MS population might more vulnerable to COVID-19 severe outcome rather that neurodegenerative. Conversely, future neurodegeneration as long-term complications of COVID-19 infections may like occur in neurodegenerative population. A large cohort of neurological patients experiencing a severe acute respiratory syndrome is need to confirm our suggestive conclusions.