Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Parkinsonism: Is There Evidence for Concern?

• Published in: Movement Disorders Vol. 35; no. 10; p. 1725
• Main Authors: Monje, Mariana H.G., Martínez‐Fernández, Raul
• Format: Journal Article Web Resource
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.10.2020; Wiley Subscription Services, Inc
• Subjects: Angiotensin-Converting Enzyme 2; Basal ganglia; Betacoronavirus - pathogenicity; Brain diseases; Central nervous system diseases; Coronavirus Infections - virology; Coronaviruses; COVID-19; Humans; Movement disorders; Pandemics; Parkinsonian Disorders - complications; Parkinsonian Disorders - virology; Peptidyl-Dipeptidase A - metabolism; Pneumonia, Viral - virology; SARS-CoV-2; Severe Acute Respiratory Syndrome - virology; Severe acute respiratory syndrome coronavirus 2
• ISSN: 0885-3185; 1531-8257
• DOI: 10.1002/mds.28247

In this context, within the last few weeks a warning has been issued that the current coronavirus 2019 (COVID‐19) pandemic could be followed by a parkinsonism epidemic.1 The arguments to justify this assumption have been based on two main arguments: (1) SARS‐CoV‐2 infection, like Parkinson's disease (PD), can present with hyposmia, suggesting an “invasion” through the olfactory bulb and potential progression to the nigrostriatal circuit as proposed for PD; and (2) the 1920s encephalitis lethargica (EL) epidemic, resulting in thousands of patients suffering from parkinsonism in its chronic stage, was historically considered to be related to the “Spanish” flu pandemic that started during the last months of World War I.2 Nevertheless, both arguments require further discussion. [...]although the ACE2 receptor is present in the human olfactory epithelium, it has not been found in the olfactory bulb.5 Thus, despite that SARS‐CoV‐2 RNA has been detected in the brain of patients who died of the infection,6 the entrance mechanisms and neuronal spread are still to be clarified. [...]notwithstanding the coincidence in time of the EL epidemic and the “Spanish” flu pandemic, the causal role of influenza virus on the former is, although not excluded, highly debated.2 In 1997, the RNA of the influenza virus was isolated from a lung tissue sample of an American serviceman who died in the 1918 pandemic.7 Subsequently, the same group looked for this RNA in brain samples from patients who had had EL, but failed to detect it.8 Despite the methodological limitations of these studies, their findings question the direct responsibility of the virus in EL. [...]the cause of EL and the putatively related parkinsonism is still unknown.