The researchers found that one of the elevated chemokines called CCL11 can directly cause microglial reactivity specifically in the hippocampus. Microglial reactivity was particularly high in the hippocampus, a brain center involved in learning and memory. This finding lines up with prior work linking microglial reactivity to poor cognitive function. The genes expressed in microglia after COVID-19 overlapped closely with those expressed by microglia in other disease contexts, including cognitive decline in aging and in neurological conditions such as Alzheimer’s disease. In their white matter, the microglia - brain cells that support neurons and “eat” cellular debris in the brain - were much more active than normal, an abnormality that persisted seven weeks after infection.Īfter mild COVID-19, analysis of gene activity in single cells uncovered more microglia with high levels of pro-inflammatory molecules called chemokines and more activity in genes involved in inflammation. Nevertheless, scientists saw more of several inflammatory cytokines in the blood and cerebrospinal fluid of the mice, increases that could be detected one and seven weeks after infection. Mice lack the cellular receptors that the SARS-CoV-2 virus uses to invade human cells, but animals in the study were genetically engineered to express the necessary receptors in the respiratory tract. After exposure to SARS-CoV-2, the mice had mild infections: They did not lose weight or behave as though they were ill, and the virus was not found in their brains. Monje and her colleagues examined brain changes in mice in which the researchers had induced SARS-CoV-2 infections confined to the respiratory system. Patients’ symptoms included impairments to attention, concentration, memory and executive function, as well as slower information processing - all of which are also common among people who experience chemo brain after cancer treatment. Stanford research published in March 2021, covering the first year of the pandemic, found that about one in four COVID-19 patients had cognitive symptoms that lingered at least two months, even after mild infections. Many COVID-19 survivors experience cognitive impairment. ![]() Because the virus caused such a strong immune response, including widespread inflammation, she suspected it might also cause cognitive problems. “When the pandemic started, I started worrying that we would see similar neurological consequences of this profoundly immunogenic virus,” Monje said. In chemo brain, damage to myelin slows their transmission. Myelin, the fatty coating insulating the long arms of the neurons, helps speed the transmission of nerve signals. They uncovered key details in how chemotherapy impairs the function of the brain’s white matter, regions of the brain normally rich in well-insulated nerve fibers that quickly transmit signals from one place to another. Monje’s team has spent two decades studying cognitive impairment after cancer. “The exciting message is that because the pathophysiology is so similar, the last couple of decades in cancer therapy-related research can guide us to treatments that may help COVID brain fog.” Nerves’ insulation damaged The overlap between what happens in COVID-19’s cognitive aftermath and chemo brain, as it’s colloquially known, could be good news for patients because it may speed research on treatments, Monje said. The study’s lead authors are Anthony Fernandez-Castaneda, PhD, a postdoctoral scholar at Stanford Anna Geraghty, PhD, an instructor of neurology at Stanford and Peiwen Lu, PhD, and graduate student Eric Song, both of Yale. Monje shares senior authorship of the study with Akiko Iwasaki, PhD, professor of immunology and of molecular, cellular and developmental biology at Yale University. “We found that even mild COVID can cause prominent inflammation in the brain that dysregulates brain cells and would be expected to contribute to cognitive impairment,” said Michelle Monje, MD, PhD, professor of neurology and neurological sciences. The findings may help guide treatments for cognitive effects of COVID-19, the scientists said. The discovery, described in a paper that published online June 12 in Cell, relied on studies of mice with mild SARS-CoV-2 infection and postmortem human brain tissue collected early in the pandemic. ![]() ![]() Brain fog after COVID-19 is biologically similar to cognitive impairment caused by cancer chemotherapy, something doctors often refer to as “chemo brain.” In both cases, excessive inflammation damages the same brain cells and processes, according to research led by Stanford University School of Medicine.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |