Study links Covid to increased risk of Alzheimer’s, Parkinson's and stroke

A new study from Denmark has found an increased risk of neurological problems such as Alzheimer's disease, Parkinson’s disease and stroke among patients with Covid-19.

The conditions are caused when there is a neurologic disorder in someone’s body.

For Alzheimer’s disease, it is progressive and destroys one's memory and other mental functions.

Parkinson's is a disorder of the central nervous system that affects movement, often including tremors.

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

It analysed the health records of over half of the Danish population, found that those who had tested positive for COVID-19 were at an increased risk.

Out of the 919,731 individuals that tested for COVID-19 within the study, the researchers found that 43,375 people who tested positive had:

• 5 times increased risk of being diagnosed with Alzheimer’s disease.
• 6 times with Parkinson’s disease.
• 7 times with ischaemic stroke and 4.8 times increased with bleeding in the brain.

The study analysed in- and outpatients in Denmark between February 2020 and November 2021, as well as influenza patients from before the pandemic period.

Researchers used statistical techniques to calculate relative risk.

Results were stratified for hospitalisation status, age, sex, and comorbidities.

However, Pardis Zarifkar, the lead author of the study, told Healthline that while previous studies have established an association with neurological syndromes.

It was not known whether COVID-19 also influences the incidence of specific neurological diseases.

He also said it is not yet fully established whether Covid-19 completely differs from other common respiratory infections.

Other studies have also suggested that it was too early to link Covid with Alzheimer's and Parkinson's only as others have linked it to blood clots that may cause heart attacks as well as stroke.

Other factors such as fatigue, depression, and anxiety after COVID-19 may also contribute to the development of neurodegenerative disorders.

However, when comparing the frequencies of these disorders after COVID-19 with those after influenza and community-acquired pneumonia, they found no significant differences, except for ischemic stroke

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

“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. Only time will tell.”

Another limitation they found was that they needed to plan future nationwide registry-based studies of pre-and post-pandemic disease rates with full nationwide follow-up to confirm these observations.

The research was published in the Frontier in Neurology.