Summary: Cognitive disorders induced by COVID-19 are linked to the IL-1β protein. Researchers have found that vaccination can reduce brain inflammation and memory loss in rodent models. This suggests that vaccines may reduce the risk of brain fog related to long COVID. Further research is needed to confirm these results in humans.
Highlights:
- IL-1β protein:Linked to cognitive impairment and reduced neurogenesis.
- Benefits of vaccination: Reduces brain inflammation and cognitive symptoms.
- search results: Vaccinated models showed less memory loss and impact on brain function.
Source:University of Western Ontario
Since the start of the COVID-19 pandemic, 10% to 30% of the general population has experienced some form of virus-induced cognitive impairment, including difficulty concentrating, brain fog, or memory loss.
This led a team of researchers to explore the mechanism behind this phenomenon and identify a specific protein that appears to be causing these cognitive changes.
A new study published in Nature immunology, led by researchers at Western and Washington University School of Medicine in St. Louis, Missouri, also examined how vaccination can help reduce the impacts of memory loss following COVID-19 infections.
The research team, including Dr. Robyn Klein, professor at the Schulich School of Medicine and Dentistry, who joined Western from the University of Washington, used rodent models to better understand the impact of COVID- 19 on cognitive impairments.
“We looked closely at their brains during acute infection, and then later after recovery, to find out what was abnormal in terms of the trafficking of different immune cells in the brain and their effects on neural cells,” said Klein, PhD. of the Canada Excellence Research Chair in Neurovirology and Neuroimmunology.
Klein said she was concerned about reports of cognitive impairment early in the pandemic, which led researchers to question whether the virus was invading the central nervous system.
Klein’s previous work studied viruses that invade the brain.
“We had previously shown that the virus could not be detected in the human brain or in the brains of hamsters, and this study also showed that the virus did not invade the central nervous system,” Klein said. This finding means that another mechanism leads to cognitive disorders.
The team identified that SARS-CoV-2 infection increased levels of interleukin-1 beta (IL-1β) in the brain, a cytokine protein that affects the immune system. The team observed that models with increased levels of IL-1β experienced a loss of neurogenesis, the process by which new neurons form in the brain, and also exhibited memory loss.
Vaccination reduces cognitive symptoms
The team concluded that IL-1β was one of the potential mechanisms behind SARS-CoV-2-induced cognitive impairment and wondered whether this could be prevented by vaccination.
The researchers then studied the impact on the vaccinated models. They found a promising correlation between vaccination and reductions in cognitive disorders such as memory loss.
The researchers showed that prior vaccination reduced brain inflammation and lowered IL-1β levels. As a result, vaccinated models experienced less impact on memory and brain function.
Klein says there is still work to be done to fully understand how vaccinations achieve this result and whether it will translate to humans.
“We know there is anecdotal evidence that vaccinated people have a much lower risk of developing this prolonged COVID-related brain fog,” Klein said.
The vaccine used in the study is not the same as vaccines available for people, Klein noted, meaning more studies will need to be done to further investigate the link between vaccination and reduced effects of long-term COVID.
“What we know is that if you are vaccinated, you have much less inflammation,” Klein said.
Vaccination aims to reduce the risk of infection, not to prevent infection altogether, she added. For example, a vaccine may protect people from developing severe pneumonia, but that does not mean it completely protects against pneumonia.
The same is likely true for cognitive impacts.
“People need to understand this about vaccines,” Klein said. “They need to know what vaccines can do and what they can’t do.”
About this memory and the latest COVID-19 research news
Author: Cynthia Fazio
Source: University of Western Ontario
Contact: Cynthia Fazio – University of Western Ontario
Picture: Image is credited to Neuroscience News
Original research: Closed access.
“Vaccination reduces central nervous system IL-1β and memory deficits after COVID-19 in mice” by Robyn Klein et al. Natural immunology
Abstract
Vaccination reduces central nervous system IL-1β and memory deficits after COVID-19 in mice
Up to 25% of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) experience post-acute cognitive sequelae.
Although millions of cases of memory impairment related to coronavirus disease 2019 (COVID-19) are accumulating worldwide, the underlying mechanisms and how vaccination reduces the risk are unknown. Interleukin-1 (IL-1), a key component of the innate immune defense against SARS-CoV-2 infection, is elevated in the hippocampus of individuals with COVID-19.
Here we show that intranasal infection of C57BL/6J mice with the beta variant of SARS-CoV-2 leads to Ly6C infiltration into the central nervous systemHi monocytes and microglial activation.
Accordingly, SARS-CoV-2, but not H1N1 influenza virus, increases IL-1β levels in the brain and induces persistent IL-1R1
loss of hippocampal neurogenesis, which promotes post-acute cognitive deficits. Vaccination with low dose of adenoviral spike protein prevents hippocampal IL-1β production during SARS-CoV-2 infection, loss of neurogenesis, and subsequent memory deficits.
Our study identifies IL-1β as one of the potential mechanisms underlying SARS-CoV-2-induced cognitive impairment in a novel mouse model, which is prevented by vaccination.