Exacerbation of motor and non-motor symptoms of Parkinson disease by severe acute respiratory syndrome coronavirus-2 infection: Are there possible links?

Background: Parkinson's disease (PD) is an ageing and progressive neurological disorder characterized by both motor (tremors, bradykinesia, rigidity) and non-motor symptoms (depression, GI disturbance, and cognitive decline). COVID-19 is a highly infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) with symptoms ranging from mild to severe cardiopulmonary dysfunction. Moreover, COVID-19 infection causes excessive release of pro-inflammatory cytokines and gut microbiome alterations and has been reported to cause neurological complications, all of which are more prevalent in PD.

Objective: This review sought to shed some light on several unanswered questions with respect to the possibility of reciprocity in pathological relationship between COVID-19 and PD, including the central issue as to whether the virus enters the neurons, astrocyte, brain vascular cells or microglia.

Methods: The review was carried out through PubMed search, using the following terms: ‘COVID-19’, ‘Parkinson disease’, ‘coronavirus’, ‘Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)’, ‘gut disturbance’.

Results: There are no clear observations for human neuronal or astrocyte expression of angiotensin converting enzyme 2 (ACE2; main receptor for SARS-CoV2 viral entry) constitutively, but are induced by inflammation. Hence, the need for comparative study in both healthy and infected brains. Recent studies suggest that COVID-19 worsened both motor and non-motor symptoms in PD patients.

Conclusion: This finding showed the possibility of direct action of COVID-19 on motor/non-motor features of PD.