Need for replication
Study coauthor Masud Husain, PhD, of University of Oxford’s cognitive neurology department, told reporters that while there is evidence from other neurologic studies that the virus can access the brain, there has been little sign the neurons themselves are affected.
“There isn’t much evidence that the virus itself attacks neurons in the brain, but it can cause inflammation, and it can activate inflammatory cells in the brain,” he said.
“And those effects are probably very important in some of the biological effects on the brain. In addition, of course, we know that the virus can change clotting and the likelihood of thrombosis in the blood, and those effects can also impact upon the brain,” he added.
Dr. Harrison said it would be helpful to replicate the results garnered from the U.S. database in other populations.
“It goes without saying that replication of these results with other electronic health records and in other countries is a priority,” he said, adding that investigations are essential into how and why the virus affects brain health.
Dr. Harrison cited a U.K. Research and Innovation–funded study called COVID CNS that will follow patients with neurologic and/or psychiatric issues during acute COVID-19 in hopes of exploring possible causes.
Beyond a reasonable doubt
Commenting on the findings, Sir Simon Wessely, MD, Regius chair of psychiatry, King’s College London, said in a release: “This is a very important paper. It confirms beyond any reasonable doubt that COVID-19 affects both brain and mind in equal measure.”
Some of these effects, including stroke and anxiety disorders, were already known, but others such as dementia and psychosis were less well known, he added.
“What is very new is the comparisons with all respiratory viruses or influenza, which suggests that these increases are specifically related to COVID-19, and not a general impact of viral infection,” Dr. Wessely said. “In general, the worse the illness, the greater the neurological or psychiatric outcomes, which is perhaps not surprising.
“The worst outcomes were in those with encephalopathy – inflammation of the brain – again, not surprising. The association with dementia was, however, small and might reflect diagnostic issues, whilst so far there doesn’t seem early evidence of a link with parkinsonism, which was a major factor after the great Spanish Flu pandemic, although the authors caution that it is too early to rule this out.”
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