SAN DIEGO, CA — More profoundly than previously believed, the virus that causes COVID-19, SARS-CoV-2, can impact the brain for months after infection. The findings were presented at Neuroscience 2022, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health.
"Long COVID," which includes the neurological fallout (a.k.a. sequelae) of a COVID-19 infection, can damage the central nervous system long after the acute symptoms of the virus have passed. Estimates report that one in five to one half of all adults are affected by at least one long COVID symptom, which includes ailments to mood and concentration. Scientists are still learning how the virus changes the brain, but it's becoming increasingly clear that the long-term effects are wide-ranging across age groups.
Today’s new findings show that:
- Using fMRI imaging, scientists found that the sensorimotor brain regions of children who contracted COVID-19 months ago now showed a higher demand for resources. (Silvia Hidalgo-Tobon, UAM-Hospital Infantil de Mexico Federico Gomez)
- To mimic SARS-CoV-2's impacts, scientists triggered inflammation in a mouse model via toll-like receptor (TLR) 7. Eight weeks later, they found hippocampal impairment in both sexes and decreased fear conditioning in males. (Natalie C. Tronson, University of Michigan)
- Scientists found that roughly one-fourth of adults who had mild COVID-19 four months prior were left with deficits in their visuoconstructive abilities. (Marco Aurelio Romano-Silva, Universidade Federal De Minas Gerais)
"This isn't the first time that a flu-like viral infection has been linked to an increased risk for dementia. But one of the most important aspects of this work is the magnitude of people potentially affected by this — millions upon millions," said Robyn Klein, The Robert E. and Louise F. Dunn Distinguished Professor of Medical Sciences, director of the Center for Neuroimmunology & Neuroinfectious Diseases, professor of medicine, pathology & immunology, and neurosciences at Washington University School of Medicine, and moderator.
"We need to move on to alternative hypotheses for these neurologic diseases; we also need to inform the public and physicians that this is a real illness and that they should be proactive in addressing it."
This research was supported by national funding agencies including the National Institutes of Health and private funding organizations. Find out more about COVID-19 and cognitive functioning on BrainFacts.org.
Press Conference Summary
- These studies offer evidence that while SARS-COV-2 does not directly invade the brain, it can still cause long-term changes to brain function through inflammation.
- While separate studies were conducted on children, adults, and mice, all highlight brain changes lasting weeks and months after infection.
Functional Implication of the Sensorimotor Network in Post-COVID-19 Children, a rs-fMRI Study
Silvia Hidalgo-Tobon, shid@xanum.uam.mx, Abstract 141.25
- Scientists tested 240 children aged between 10 and 13 years (240 subjects in all) who had COVID-19 between four and 15 months ago and recovered. Scientists looked for variations in brain activity using rs-fMRI.
- Compared with control subjects, those who had contracted COVID-19 had higher temporal correlations in three clusters of the brain, including the precentral and postcentral gyrus and supplementary motor area.
- Preliminary results suggest children's brains may be more resource-demanding after COVID-19.
COVID-19-Like Inflammation Causes Persistent Memory Deficits in Aging Mice
Natalie C. Tronson, ntronson@umich.edu, Abstract 553.05
- COVID-19-related inflammation can change memory and cognition. The virus is known to activate the immune system via Toll-Like Receptors (TLRs). TLR3 and TLR4 activation has been studied, but TLR7 and TLR8 less so.
- Using a mouse model, scientists examined the hypothesis that TLR7-triggered inflammation may also cause COVID-like brain fog and other cognitive impairments.
- Eight weeks after activating the inflammation, both males and females experienced hippocampus-related impairments of novel object recognition. In male mice, scientists saw decreased context-dependent fear conditioning.
Visuoconstructional Impairment Following Mild COVID-19
Marco Aurelio Romano-Silva, romanosilva@gmail.com, Abstract 700.05
- The majority of COVID-19 cases worldwide have been mild-to-moderate. While cognitive impairments have been found in severe cases of COVID-19, what is there to find in mild cases?
- Scientists studied adults who recovered from mild cases of COVID-19 four months previously. MRI and PET imaging showed that, in approximately a quarter of patients, there was a specific visuoconstructive deficit associated with molecular and clinical changes.
- This is preliminary evidence that cognitive deficit from neuroinflammation may result from even mild COVID-19 symptoms.