The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2, has been responsible, until April 2020, for nearly 2.5 million confirmed cases and over 150 000 deaths in 210 countries worldwide. The disease may cause pneumonia and acute respiratory failure. However, neurologic symptoms have also been reported, namely anosmia and ageusia, even without being accompanied by nasal obstruction or rhinorrhea, suggesting the involvement of olfactory and gustatory nerves.
Injury of the brainstem and of the olfactory pathway may cause sleep disorders and respiratory failure. There is also evidence of the neurotropism of SARS-CoV-2 from histological observations of brain tissue, from the presence of the virus genome in the cerebrospinal fluid of one COVID-19 case, presenting with encephalitis. Virus infections may cause acute brain injury and there is evidence of the association of viral infections with neurodegenerative diseases. Infection by SARS-CoV-2 virus has the potential to cause or initiate neurodegenerative diseases, such as dementia and Parkinson’s disease that may manifest years later. Cognitive decline precedes dementia and anosmia and sleep disorders are prodromal markers of Parkinson’s disease. Therefore, this project aims to assess the occurrence of neurologic symptoms, particularly, anosmia, ageusia, sleep disorders and cognitive decline, and Parkinson’s disease and dementia in the population covered by the Local Health Unit of Matosinhos and by Hospital São Sebastião, in Santa Maria da Feira, and to compare the incidence of cognitive decline in survivors of COVID-19 and persons with no evidence of previous SARS-CoV-2 infection, over a follow-up period of two years, since January 2020.
Mild, moderate and severe cases of COVID-19, recruited among those clinically followed at home and among hospitalized patients, will be compared to participants from the general population of Matosinhos and participants hospitalized in the same hospital and clinical department, matched by age, sex, the severity of the illness, hospital and clinical department, and duration of hospitalization. Participants will be followed for two years with tools adapted for remote monitoring to increase the feasibility of the evaluations, in a context of physical distancing to minimize the risk of infection, which is expected to remain in place for the next months or years. The research team developed a web-based instrument for cognitive monitoring, which allows for cognitive evaluations over time with reduced learning effects by participants. This tool has already been used in other cohorts followed by the research team and has shown high discriminative ability. Positive cases detected by screening will be evaluated by neurologists, preferentially by videoconference, or according to the procedures in place at the moment in the respective hospitals.
Our results will provide robust estimates of the incidence of prodromal manifestations of neurodegenerative diseases related to SARS-CoV-2 infection and of Parkinson’s disease, mild cognitive impairment and dementia among COVID-19 survivors affected with mild, moderate and severe SARS-CoV-2 infection. The longitudinal design with a two-year follow-up will allow for assessing the time course of these complications and potential long-term neurological effects of the SARS-CoV-2 infection. The research team has a large experience in conducting longitudinal prospective studies to evaluate cognitive decline and includes epidemiologists and clinicians with special expertise in neurodegenerative diseases, as well as Public Health professionals and clinicians that have been closely involved in the management of the COVID-19 epidemic. The refinement of the methodology to remote administration will be performed in a project to be ended in 2020.