27 June 2022 | Monday | News
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Covid-19-positive outpatients have a higher risk of neurodegenerative disorders compared to people who tested negative for the virus, a new study presented today at the 8th Congress of the European Academy of Neurology (EAN) has shown.
The study, which analyzed the health records of more than half of the Danish population, found that those who had tested positive for COVID-19 had an increased risk of Alzheimer's disease, Parkinson's disease and ischemic stroke.
Of the 919,731 people who tested for COVID-19 in the study, the researchers found that the 43,375 people who tested positive had a 3.5-fold increased risk of being diagnosed with Alzheimer's disease, 2.6 times with Parkinson's disease, 2.7 times with an ischemic stroke, and 4.8 times higher with intracerebral hemorrhage. While neuroinflammation may contribute to the accelerated development of neurodegenerative disorders, the authors highlighted the implications of the scientific approach on the long-term sequelae after COVID-19.
The study looked at Danish inpatients and outpatients between February 2020 and November 2021, as well as flu patients from the corresponding pre-pandemic period. The researchers used statistical techniques to calculate relative risk and the results were stratified by hospital status, age, sex and comorbidities.
Dr Pardis Zarifkar, Lead Author from the Department of Neurology, Rigshospitalet, Copenhagen, Denmark, explained: "More than two years after the onset of the COVID-19 pandemic, the precise nature and evolution of the effects of COVID-19 on neurological disorders remained uncharacterised. Previous studies have established an association with neurological syndromes, but so far it is unknown whether COVID-19 also influences the incidence of specific neurological diseases and whether it differs from other respiratory infections."
However, the increased risk of most neurological diseases was not higher in COVID-19-positive patients than in people who had been diagnosed with flu or other respiratory illnesses. Patients with COVID-19 had a 1.7-fold increased risk of ischemic stroke compared to influenza and bacterial pneumonia in patients over the age of 80.
The frequency of other neurodegenerative diseases such as multiple sclerosis, myasthenia gravis, Guillain-Barré syndrome and narcolepsy did not increase after COVID-19, influenza or pneumonia.
Dr Pardis Zarifkar added: "These findings will inform our understanding of the long-term effect of COVID-19 on the body and the role infections play in neurodegenerative diseases and strokes."