Most of what we know about how COVID can affect the brain has come from studies of severe infection. In people with severe COVID, inflammatory cells from outside the brain can enter brain tissue and spread inflammation. There may be changes to blood vessels. Brain cells can even have changes similar to those seen in people with Alzheimer’s disease.
For the first time, a new study has investigated the effects of mild COVID (that is, infection that doesn’t lead to a hospital admission) on the brain. The findings may further explain some of the brain changes contributing to long COVID.
Brain scans and tests show changes
Many people who have had COVID report feelings of “brain fog”, fatigue and problems with concentration and memory long after their initial symptoms resolve. These problems, collectively referred to as “long COVID”, may last for months even after mild infection.
Long COVID is very common, and may affect more than half of the people who catch COVID, even if they have a mild case.
Scientists collected data as part of the massive UK Biobank database. They looked at brain magnetic resonance imaging (MRI) scans and tests of brain function in 785 volunteers who were assessed before the pandemic. They then compared this to the same data collected three years later, when about half of those participants had mild COVID infection, and the other half had not caught COVID. This allowed the scientists to determine the specific effects of mild COVID infection on brain structure and function.
The group who had mild COVID an average of five months beforehand had thinning of brain tissue in several brain regions, ranging from 0.2% to around 2% compared to their pre-COVID scan. This is equivalent to between one and six years of normal brain ageing. Affected brain regions included the parahippocampal gyrus (an area related to memory) and the orbitofrontal cortex, which is located at the front of the brain and is important for smell and taste.
The post-COVID group also showed a reduction in overall brain size between their MRI scans that wasn’t seen in the non-COVID group, and had altered connections between different brain regions in the olfactory cortex, an area related to smell.
They performed worse in a test for attention and mental flexibility, a finding that was associated with volume reductions within a part of the cerebellum related to smell and social relationships.
Comparing to other illnesses
To show these changes were specific to COVID and not just related to having a respiratory illness, the scientists also looked at a group of people who had pneumonia. They did not see the same changes, confirming they are related to COVID.
Decreases in brain volume are common to many brain diseases and disorders associated with degeneration, and have been found in people with mild cognitive impairment, Alzheimer’s disease, depression and traumatic brain injury, among others.
Problems with memory and attention are also frequent for people with these diseases and disorders, indicating mild COVID infection may accelerate brain degeneration. These changes could explain the reported symptoms of long COVID, such as brain fog.
The study did not look at the mechanisms of mild COVID in the brain. However, the authors suggest this could be due to inflammation, degeneration which spreads through the brain pathways associated with smell, or sensory deprivation due to loss of smell.
Read more from the source:
News
Repurposed drugs could calm the immune system’s response to nanomedicine
An international study led by researchers at the University of Colorado Anschutz Medical Campus has identified a promising strategy to enhance the safety of nanomedicines, advanced therapies often used in cancer and vaccine treatments, [...]
Nano-Enhanced Hydrogel Strategies for Cartilage Repair
A recent article in Engineering describes the development of a protein-based nanocomposite hydrogel designed to deliver two therapeutic agents—dexamethasone (Dex) and kartogenin (KGN)—to support cartilage repair. The hydrogel is engineered to modulate immune responses and promote [...]
New Cancer Drug Blocks Tumors Without Debilitating Side Effects
A new drug targets RAS-PI3Kα pathways without harmful side effects. It was developed using high-performance computing and AI. A new cancer drug candidate, developed through a collaboration between Lawrence Livermore National Laboratory (LLNL), BridgeBio Oncology [...]
Scientists Are Pretty Close to Replicating the First Thing That Ever Lived
For 400 million years, a leading hypothesis claims, Earth was an “RNA World,” meaning that life must’ve first replicated from RNA before the arrival of proteins and DNA. Unfortunately, scientists have failed to find [...]
Why ‘Peniaphobia’ Is Exploding Among Young People (And Why We Should Be Concerned)
An insidious illness is taking hold among a growing proportion of young people. Little known to the general public, peniaphobia—the fear of becoming poor—is gaining ground among teens and young adults. Discover the causes [...]
Team finds flawed data in recent study relevant to coronavirus antiviral development
The COVID pandemic illustrated how urgently we need antiviral medications capable of treating coronavirus infections. To aid this effort, researchers quickly homed in on part of SARS-CoV-2's molecular structure known as the NiRAN domain—an [...]
Drug-Coated Neural Implants Reduce Immune Rejection
Summary: A new study shows that coating neural prosthetic implants with the anti-inflammatory drug dexamethasone helps reduce the body’s immune response and scar tissue formation. This strategy enhances the long-term performance and stability of electrodes [...]
Scientists discover cancer-fighting bacteria that ‘soak up’ forever chemicals in the body
A family of healthy bacteria may help 'soak up' toxic forever chemicals in the body, warding off their cancerous effects. Forever chemicals, also known as PFAS (per- and polyfluoroalkyl substances), are toxic chemicals that [...]
Johns Hopkins Researchers Uncover a New Way To Kill Cancer Cells
A new study reveals that blocking ribosomal RNA production rewires cancer cell behavior and could help treat genetically unstable tumors. Researchers at the Johns Hopkins Kimmel Cancer Center and the Department of Radiation Oncology and Molecular [...]
AI matches doctors in mapping lung tumors for radiation therapy
In radiation therapy, precision can save lives. Oncologists must carefully map the size and location of a tumor before delivering high-dose radiation to destroy cancer cells while sparing healthy tissue. But this process, called [...]
Scientists Finally “See” Key Protein That Controls Inflammation
Researchers used advanced microscopy to uncover important protein structures. For the first time, two important protein structures in the human body are being visualized, thanks in part to cutting-edge technology at the University of [...]
AI tool detects 9 types of dementia from a single brain scan
Mayo Clinic researchers have developed a new artificial intelligence (AI) tool that helps clinicians identify brain activity patterns linked to nine types of dementia, including Alzheimer's disease, using a single, widely available scan—a transformative [...]
Is plastic packaging putting more than just food on your plate?
New research reveals that common food packaging and utensils can shed microscopic plastics into our food, prompting urgent calls for stricter testing and updated regulations to protect public health. Beyond microplastics: The analysis intentionally [...]
Aging Spreads Through the Bloodstream
Summary: New research reveals that aging isn’t just a local cellular process—it can spread throughout the body via the bloodstream. A redox-sensitive protein called ReHMGB1, secreted by senescent cells, was found to trigger aging features [...]
AI and nanomedicine find rare biomarkers for prostrate cancer and atherosclerosis
Imagine a stadium packed with 75,000 fans, all wearing green and white jerseys—except one person in a solid green shirt. Finding that person would be tough. That's how hard it is for scientists to [...]
Are Pesticides Breeding the Next Pandemic? Experts Warn of Fungal Superbugs
Fungicides used in agriculture have been linked to an increase in resistance to antifungal drugs in both humans and animals. Fungal infections are on the rise, and two UC Davis infectious disease experts, Dr. George Thompson [...]
