COVID-19 and Parkinson’s Disease: Keeping an Eye on a Possible Connection
Until a few weeks ago, there was no evidence that patients with COVID-19 were at increased risk for developing movement disorders. We and others had hypothesized and speculated on a possible connection, based on evidence connecting other viral infections with Parkinson’s disease (PD). Now, the knowledge accumulated over the past several months is starting to show that our hypothesis might be right. A recent report from Cohen and colleagues, in Lancet Neurology, suggests that a 45 year-old COVID-19 patient developed PD after SARS-CoV-2 infection. The mechanisms leading to the degeneration of nigrostriatal neurons are unclear. A unique interaction between genes and the infection might have played a role, but other possibilities need to be considered. We know that SARS-CoV-2, the virus responsible for COVID-19, enters cells by strongly interacting with the ACE2 receptor (Yan et al. 2020). This receptor is expressed by cells in the respiratory system, and this explains why they may be particularly vulnerable. However, the ACE2 receptor is also expressed in several other tissues, including in the central nervous system, suggesting it may also directly affect neuronal cells in the brain. Indeed, recent studies have identified coronaviruses in the central nervous system, including in patients with neurodegenerative disorders (Gómez-Pinedo et al. 2020). This suggests there may be direct effects of SARS-CoV-2 in the brain.
When we consider the major risk factors for the severity of COVID-19, the common denominator is the immune system (Lippi et al. 2020). Aging and other conditions known to impact on the performance of the immune system significantly increase the risk for a worse prognosis of COVID-19. Although neuropathological examinations of COVID-19 brains are scarce, signs of neuroinflammation have been detected, supporting the idea that altered immune responses in the brain may be taking place. Therefore, given the established connection between neuroinflammation and neurodegeneration, it is possible that the connection between COVID-19 and movement disorders may also result from altered immune responses in the brain.
These possibilities are still speculative at this point, require intense investigation and accurate clinical assessments in order to avoid unnecessary alarm and unsettlement. We need to remain vigilant, and take the necessary preventive measures to protect those at risk. Therefore, as Sulzer and colleagues recently suggested, we should already define consensus guidelines for treating PD patients with COVID-19, and to support initiatives for following COVID-19 patients over time, in order to be able to detect any possible abnormal increased in the prevalence of PD or other neurodegenerative disorders.
Prof. Dr. Tiago Fleming Outiero, PhD, presented at the WPC 2016, spoke on the WPC Scientific Update 2015 webcast and currently sits on the Basic Science Subcommittee of the WPC 2022 Program Committee. He is Director of the Department of Experimental Neurodegeneration, University Medical Center Goettingen in Goettingen, Germany.
Ideas and opinions expressed in this post reflect that of the authors solely. They do not reflect the opinions or positions of the World Parkinson Coalition®