Brain changes: the ongoing effects of COVID-19

SAN DIEGO, Calif.
– More serious than previously thought, SARS-CoV-2, the virus that causes COVID-19, can affect the brain
months after infection.
The findings were presented at the Neuroscience 2022 Annual Conference, which is also the world's largest source
of research news on brain science and health.
"Long COVID," including the neurological consequences of COVID-19 infection (also known as sequelae), can damage the central nervous system
long after the acute symptoms of the virus have passed.
It is estimated that between one in five and one in half adults are affected by at least one prolonged COVID symptom, including mood and attention disorders
.
Scientists are still studying how the virus alters the brain, but it is becoming increasingly clear that its long-term effects are wide-ranging, spanning all age groups
.
Today's new findings show:

• Through MRI, the scientists found that sensorimotor brain regions in children who contracted COVID-19 a few months ago now show a higher demand
  for resources.
  (Silvia Hidalgo-Tobon, Uam Mexican Baby Hospital Federico Gomez)

• To mimic the effects of SARS-CoV-2, the scientists triggered inflammation
  in a mouse model using toll-like receptor (TLR) 7.
  After eight weeks, they found that both males and females had hippocampal injuries, and the males' fear conditioning was reduced
  .
  (Natalie C.
  Tronson, University of Michigan)

• The scientists found that about a quarter of adults who contracted mild COVID-19 4 months ago had deficits
  in their ability to construct their vision.
  (Marco Aurelio Romano-Silva, Federal University of Minas Gerais)

"This is not the first time that viral infections have been linked
to an increased risk of dementia.
But one of the most important aspects of this work is the size of the potentially affected population — millions of people," said
Robin Klein, the Robert and Louis F.
Dunn Distinguished Professor of Medical Sciences, director of the Center for Neuroimmunology and Neuroinfectious Diseases, and professor of medicine, pathology, immunology, and neuroscience at Washington University School of Medicine.
"We need alternative hypotheses for these neurological diseases; We also need to tell the public and doctors that this is a real disease and that they should be actively dealing with it
.
The study was supported
by state funding agencies and privately funded organizations, including the National Institutes of Health.
Sign in BrainFacts.
org to learn more about
COVID-19 and cognitive function.
THESE STUDIES PROVIDE EVIDENCE THAT ALTHOUGH SARS-COV-2 DOES NOT INVADE THE BRAIN DIRECTLY, IT CAN STILL CAUSE LONG-TERM CHANGES
IN BRAIN FUNCTION THROUGH INFLAMMATION.
- Although separate studies were conducted on children, adults, and mice, all highlighted brain changes
that persisted weeks or months after infection.
Functional significance
of sensorimotor networks in children after COVID-19.

• The scientists tested 240 children between the ages of 10 and 13 (240 subjects in total) who had contracted COVID-19 4 to 15 months ago and recovered
  .
  Scientists use rs-fMRI to look for changes in
  brain activity.
  

• People infected with COVID-19 had a higher temporal correlation in three clusters of the brain, including the anterior central gyrus, posterior central gyrus, and assisted motor areas
  compared to controls.
  

• Preliminary results suggest that children's brains may be more in need of resources
  after COVID-19.
  

Natalie C.
Tronson, ntronson@umich.
edu, abstract 553.
05

• The inflammation associated with COVID -19 can alter memory and cognition
  .
  The virus is known to activate the immune system
  through toll-like receptors (TLRs).
  Activation of TLR3 and TLR4 has been studied, but TLR7 and TLR8 have been less
  studied.
  

• Using mouse models, the scientists tested the hypothesis
  that TLR7-induced inflammation may also contribute to COVID-like brain fog and other cognitive disorders.
  

• After 8 weeks of activating the inflammation, both men and women experienced hippocampal damage
  associated with recognition of new objects.
  In male mice, the scientists found that environment-dependent fear conditioning was reduced
  .
  

Marco Aurelio Romano-Silva, romanosilva@gmail.
com, abstract 700.
05

• Most COVID-19 cases globally are mild to moderate
  .
  While cognitive impairment has been found in severe cases of COVID-19, what can be found in mild cases?

• The scientists studied adults
  who recovered from mild COVID-19 4 months ago.
  MRI and PET imaging revealed that in about a quarter of patients, there were specific visual construction defects
  associated with molecular and clinical changes.
  

• This is preliminary evidence that even mild COVID-19 symptoms may contribute to cognitive impairment
  due to neuroinflammation.