COVID-19 could be linked to an increased risk of neurodegenerative disorders such as Alzheimer’s disease and Parkinson’s disease, a study carried out at Rigshospitalet, Copenhagen, has found.


The researchers statistically analysed records taken from both in- and outpatients in Denmark shortly after the coronavirus pandemic struck between February 2020 and November 2021.

Of the 919,731 patients that tested for COVID-19, they found that the 43,375 who tested positive had a 3.5 times increased risk of being diagnosed with Alzheimer’s disease, 2.6 times with Parkinson’s disease, 2.7 times with stroke and a 4.8 times increased risk of with suffering from bleeding in the brain.

The increase in risk of neurological diseases was comparable to patients who had contracted influenza or other respiratory illnesses, but COVID patients over the age of 80 were seen to have a 1.7 times increased risk of stroke compared to influenza and pneumonia patients.

“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,” said lead author Dr Pardis Zarifkar, from the Department of Neurology, Rigshospitalet.

“Previous studies have established an association with neurological syndromes, but until now it is unknown whether COVID-19 also influences the incidence of specific neurological diseases and whether it differs from other respiratory infections."

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The effect may be due to inflammation in the brain caused by the virus but more work is needed on the effects of long COVID, the researchers say.

However, there was no increase in the risk of other neurodegenerative illnesses such as multiple sclerosis, myasthenia gravis, Guillain-Barré syndrome.

“We found support for an increased risk of being diagnosed with neurodegenerative and cerebrovascular disorders in COVID-19 positive compared to COVID-19 negative patients, which must be confirmed or refuted by large registry studies in the near future,” said Zarifkar.

“Reassuringly, apart for ischemic stroke, most neurological disorders do not appear to be more frequent after COVID-19 than after influenza or community-acquired bacterial pneumonia.

“These findings will help to inform our understanding of the long-term effect of COVID-19 on the body and the role that infections play in neurodegenerative diseases and stroke.”

The study was presented at the 8th European Academy of Neurology (EAN) Congress in Vienna.

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Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.