<p>The SARS-CoV-2 virus may increase the likelihood of the brain degeneration found in Parkinson's disease, according to a study in mice.</p>.<p>Covid-19 patients commonly report symptoms such as brain fog, headaches, and insomnia, complications which are not new after a viral infection, the researchers said.</p>.<p>It took nearly a decade for patients to develop the neurological disease known as "post-encephalic parkinsonism” after the 1918 influenza pandemic, they said.</p>.<p>The study, published in the journal Movement Disorders, found that the SARS-CoV-2 virus could raise the brain's susceptibility to a toxin that causes the death of nerve cells seen in Parkinson’s disease.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/national/experts-blame-peoples-casual-attitude-for-rising-covid-cases-in-country-1119733.html">Experts blame people's 'casual attitude' for rising Covid cases in country</a></strong></p>.<p>"Parkinson's is a rare disease that affects 2 per cent of the population above 55 years, so the increase in risk is not necessarily a cause for panic,” said study first author Richard Smeyne, from Thomas Jefferson University, US.</p>.<p>"But understanding how coronavirus impacts the brain can help us prepare for the long-term consequences of this pandemic,” Smeyne said.</p>.<p>The study expands on prior findings from the Smeyne lab indicating that viruses can increase the susceptibility of brain cells or neurons to damage or death.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/national/india-reports-12781-new-covid-19-cases-18-deaths-1119683.html">India reports 12,781 new Covid-19 cases, 18 deaths</a></strong></p>.<p>In that study, the researchers discovered that mice exposed to the H1N1 influenza strain that caused the 2009 flu pandemic were more vulnerable to MPTP.</p>.<p>MPTP is a toxin known to cause some of the characteristic symptoms of Parkinson's disease, most notably the loss of neurons that express the chemical dopamine and increased inflammation in the basal ganglia, a brain region that is crucial for movement.</p>.<p>The latest study employed mice that were genetically altered to express the human ACE-2 receptor, which the SARS-CoV-2 virus utilises to get access to the cells in our airways.</p>.<p>These mice were infected with SARS-CoV-2 and then allowed to recover, the researchers said.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/science-and-environment/the-inside-story-of-recovery-how-the-world-s-largest-covid-19-trial-transformed-treatment-1119692.html">The inside story of Recovery: How the world’s largest Covid-19 trial transformed treatment</a></strong></p>.<p>The dosage used in this research corresponds to a mild Covid-19 infection in people, with around 80 per cent of infected mice surviving, they said.</p>.<p>Thirty-eight days after the surviving mice had recovered, one group was given a modest dosage of MPTP that would not ordinarily trigger neuron loss.</p>.<p>The control group was given saline. The animals were sacrificed and their brains were examined two weeks later.</p>.<p>The researchers found that Covid-19 infection alone had no impact on dopaminergic neurons in the basal ganglia.</p>.<p><strong>Read | <a href="https://www.deccanherald.com/state/top-karnataka-stories/talking-can-spread-covid-as-much-as-coughing-finds-iisc-study-1119126.html" target="_blank">Talking can spread Covid as much as coughing, finds IISc study</a></strong></p>.<p>However, mice given a modest dosage of MPTP after recovering from infection demonstrated the classic pattern of neuron loss found in Parkinson’s disease.</p>.<p>This increased sensitivity following Covid-19 infection was comparable to what was reported in the influenza trial, suggesting that both viruses might cause an equal increase in the risk of developing Parkinson's.</p>.<p>"We think about a 'multi-hit’ hypothesis for Parkinson's -- the virus itself does not kill the neurons, but it does make them more susceptible to a 'second hit', such as a toxin or bacteria or even an underlying genetic mutation," Smeyne explained.</p>.<p>Both influenza and SARS-CoV2 have been found to cause a "cytokine storm" or an overproduction of pro-inflammatory chemicals.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/opinion/panorama/why-haven-t-centre-nia-probed-origins-of-coronavirus-1119571.html">Why haven’t Centre, NIA probed origins of coronavirus?</a></strong></p>.<p>These chemicals can cross the blood-brain barrier and activate the brain’s immune cells – microglia.</p>.<p>The researchers found increased numbers of activated microglia in the basal ganglia of mice that recovered from SARS-CoV2 and received MPTP.</p>.<p>While the mechanism is not fully understood, they believe the increased microglia inflame the basal ganglia and cause cellular stress. This then lowers the neurons’ threshold to withstand subsequent stress.</p>.<p>"We were concerned about the long-term consequences of viral infection," said Peter Schmidt, a neuroscientist from New York University in the US, who co-led the study.</p>.<p>The researchers are planning to determine whether vaccines can mitigate the experimental increase in Parkinson's pathology linked to prior SARS-CoV-2 infection.</p>.<p>They are also testing other variants of the virus, as well as doses that correspond to milder cases in humans. </p>
<p>The SARS-CoV-2 virus may increase the likelihood of the brain degeneration found in Parkinson's disease, according to a study in mice.</p>.<p>Covid-19 patients commonly report symptoms such as brain fog, headaches, and insomnia, complications which are not new after a viral infection, the researchers said.</p>.<p>It took nearly a decade for patients to develop the neurological disease known as "post-encephalic parkinsonism” after the 1918 influenza pandemic, they said.</p>.<p>The study, published in the journal Movement Disorders, found that the SARS-CoV-2 virus could raise the brain's susceptibility to a toxin that causes the death of nerve cells seen in Parkinson’s disease.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/national/experts-blame-peoples-casual-attitude-for-rising-covid-cases-in-country-1119733.html">Experts blame people's 'casual attitude' for rising Covid cases in country</a></strong></p>.<p>"Parkinson's is a rare disease that affects 2 per cent of the population above 55 years, so the increase in risk is not necessarily a cause for panic,” said study first author Richard Smeyne, from Thomas Jefferson University, US.</p>.<p>"But understanding how coronavirus impacts the brain can help us prepare for the long-term consequences of this pandemic,” Smeyne said.</p>.<p>The study expands on prior findings from the Smeyne lab indicating that viruses can increase the susceptibility of brain cells or neurons to damage or death.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/national/india-reports-12781-new-covid-19-cases-18-deaths-1119683.html">India reports 12,781 new Covid-19 cases, 18 deaths</a></strong></p>.<p>In that study, the researchers discovered that mice exposed to the H1N1 influenza strain that caused the 2009 flu pandemic were more vulnerable to MPTP.</p>.<p>MPTP is a toxin known to cause some of the characteristic symptoms of Parkinson's disease, most notably the loss of neurons that express the chemical dopamine and increased inflammation in the basal ganglia, a brain region that is crucial for movement.</p>.<p>The latest study employed mice that were genetically altered to express the human ACE-2 receptor, which the SARS-CoV-2 virus utilises to get access to the cells in our airways.</p>.<p>These mice were infected with SARS-CoV-2 and then allowed to recover, the researchers said.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/science-and-environment/the-inside-story-of-recovery-how-the-world-s-largest-covid-19-trial-transformed-treatment-1119692.html">The inside story of Recovery: How the world’s largest Covid-19 trial transformed treatment</a></strong></p>.<p>The dosage used in this research corresponds to a mild Covid-19 infection in people, with around 80 per cent of infected mice surviving, they said.</p>.<p>Thirty-eight days after the surviving mice had recovered, one group was given a modest dosage of MPTP that would not ordinarily trigger neuron loss.</p>.<p>The control group was given saline. The animals were sacrificed and their brains were examined two weeks later.</p>.<p>The researchers found that Covid-19 infection alone had no impact on dopaminergic neurons in the basal ganglia.</p>.<p><strong>Read | <a href="https://www.deccanherald.com/state/top-karnataka-stories/talking-can-spread-covid-as-much-as-coughing-finds-iisc-study-1119126.html" target="_blank">Talking can spread Covid as much as coughing, finds IISc study</a></strong></p>.<p>However, mice given a modest dosage of MPTP after recovering from infection demonstrated the classic pattern of neuron loss found in Parkinson’s disease.</p>.<p>This increased sensitivity following Covid-19 infection was comparable to what was reported in the influenza trial, suggesting that both viruses might cause an equal increase in the risk of developing Parkinson's.</p>.<p>"We think about a 'multi-hit’ hypothesis for Parkinson's -- the virus itself does not kill the neurons, but it does make them more susceptible to a 'second hit', such as a toxin or bacteria or even an underlying genetic mutation," Smeyne explained.</p>.<p>Both influenza and SARS-CoV2 have been found to cause a "cytokine storm" or an overproduction of pro-inflammatory chemicals.</p>.<p><strong>Also Read | <a href="https://www.deccanherald.com/opinion/panorama/why-haven-t-centre-nia-probed-origins-of-coronavirus-1119571.html">Why haven’t Centre, NIA probed origins of coronavirus?</a></strong></p>.<p>These chemicals can cross the blood-brain barrier and activate the brain’s immune cells – microglia.</p>.<p>The researchers found increased numbers of activated microglia in the basal ganglia of mice that recovered from SARS-CoV2 and received MPTP.</p>.<p>While the mechanism is not fully understood, they believe the increased microglia inflame the basal ganglia and cause cellular stress. This then lowers the neurons’ threshold to withstand subsequent stress.</p>.<p>"We were concerned about the long-term consequences of viral infection," said Peter Schmidt, a neuroscientist from New York University in the US, who co-led the study.</p>.<p>The researchers are planning to determine whether vaccines can mitigate the experimental increase in Parkinson's pathology linked to prior SARS-CoV-2 infection.</p>.<p>They are also testing other variants of the virus, as well as doses that correspond to milder cases in humans. </p>