Of the 9,19,731 individuals who were tested for Covid within the study, researchers 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 ischaemic stroke and a 4.8 times increased with intracerebral haemorrhage (bleeding in the brain).
Previous studies have also provided evidence for substantial neurological and psychiatric morbidity in the six months after Covid infection.
A study published in 'The Lancet' in April 2021 showed risks were greatest in, but not limited to, patients who had severe Covid. It studied 2,36,379 patients diagnosed with Covid and found the estimated incidence of a neurological or psychiatric diagnosis among these persons in the following six months to be 33·62 per cent.
The Denmark study analysed in and outpatients in the country between February 2020 and November 2021, as well as influenza patients from the corresponding pre-pandemic period.
“More than two years after the onset of the pandemic, the precise nature and evolution of the effects of Covid on neurological disorders remained uncharacterised,” said Pardis Zarifkar, lead author from the Department of Neurology, Rigshospitalet, Copenhagen, Denmark.