Brain shrinkage, cognitive decline, long COVID after infection: what researchers have discovered so far

Brain shrinkage and cognitive decline in Covid patients

An Oxford University study published in the journal Nature yesterday (March 7th) found that COVID-19 can cause the brain to shrink, reduce grey matter in the regions that control emotion and memory as well as damage areas that control the sense of smell. These brain changes, detected months after infection, included shrinkage in size equivalent to as much as 10 years of normal aging.

“There is strong evidence for brain-related abnormalities in COVID-19,” the researchers concluded in their study. Even in mild cases, participants in the research showed “a worsening of executive function” responsible for focus and organising. The study investigated brain changes in 785 UK Biobank participants aged 51 to 81 who were imaged twice. 401 cases tested positive for infection with SARS-CoV-2 between their two scans, with 141 days on average separating their diagnosis and second scan. There were 384 controls. The brain imaging not only showed a shrinkage in brain size in infected participants, but the infected participants also showed larger cognitive decline. On average, brain sizes shrank between 0.2% and 2%. A 2% reduction represents around 10 years of aging.

What researchers have discovered about Long Covid

On a separate note, dozens of studies on Long Covid have been published in recent months. In Long Covid patients, researchers have found evidence of sustained inflammation and activation of the immune response months after initial infection. Research to be presented at the European Congress of Clinical Microbiology and Infectious Diseases in April 2022 suggests that damage to the vagus nerve (which extends from the brain down the torso and is responsible for the regulation of internal organ functions, such as digestion, heart rate, and respiratory rate, as well as vasomotor activity, and certain reflex actions, such as coughing, sneezing, swallowing, and vomiting) is behind many Long Covid symptoms. After studying almost 350 patients with Long Covid, the researchers found that 66% had symptoms indicative of vagus nerve damage, including abnormal heart rate, dizziness, and gastrointestinal problems.

Other studies argue that tiny “microclots” in the blood may cause many Long Covid symptoms by preventing oxygen from reaching the body’s tissues. Intolerance to exercise, experienced by Long Covid sufferers, may be related to poor oxygen delivery.

Other researchers believe that remnants of the COVID-19 virus may linger in the body, potentially causing lasting symptoms. It is also possible that, for some people, COVID-19 pushes the immune system into a hyperactive state, essentially causing it to attack itself.

Researchers have, so far, found 4 key risk factors associated with developing Long Covid:

  • a type 2 diabetes diagnosis
  • genetic material from the SARS-CoV-2 virus in the blood
  • evidence of Epstein-Barr virus in the blood
  • the presence of autoantibodies- molecules that attack the body’s own tissues, instead of foreign pathogens like a virus

Experts now believe Long Covid is part of a much wider network of chronic diseases. It seems to overlap significantly with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a condition that can manifest after viral illnesses and leads to debilitating exhaustion. Some experts believe that some people with Long Covid meet the diagnostic criteria of ME/ CFS.

Is there anything we can do to prevent severe infection or Long Covid?

  1. Gut health is key. More than two thirds of immune cells in the human body reside in our gut. Our gut microbiome directly impacts our immune system. The Chinese University of Hong Kong (CUHK) found that that certain strains of bacteria (including Bifidobacterium adolescentis) were missing in the intestines of patients with Long Covid. CUHK has since developed a special microbiome immunity formula including those strains. A clinical study by CUHK showed that COVID-19 patients who received the microbiome immunity formula had complete symptom resolution, reduced proinflammatory markers, increased favorable gut bacteria and neutralizing antibody compared with subjects who did not take the formula.
  2. Protect your lungs and brain. Studies show that NAC (N-Acetyl-Cysteine) can boost the immune system, break up mucus (so the body can cough it up easily) and reduce inflammation. Safe and well tolerated, NAC is a precursor to glutathione and regulates glutamate levels in the brain. Glutathione is a potent antioxidant that helps reduce brain cell oxidative damage, while the neurotransmitter glutamate is involved in a broad range of learning, behavior and memory functions. Serious COVID-19 patients have increased levels of reactive oxygen species (ROS) and free radicals, often presenting with glutathione depletion, which can prompt a cytokine storm. Studies in 2020 and 2021 found that NAC is a promising molecule that can help prevent severe COVID-19 infections as well as protect the lungs and brain. There are several ongoing clinical trials in progress determining the potential use of NAC in treating COVID-19 infections. The FDA is currently looking to ban the sale of NAC as a dietary supplement (and potentially sell it as a drug).
  3. Prevent unnecessary inflammation/ Promote optimal inflammation response. An overexuberant immune response to COVID-19 can cause excessive inflammation in the lungs and other parts of the body. MIS (Multi-system Inflammatory Syndrome) is a rare but potentially life-threatening condition associated with COVID in which various body parts become inflamed, including the heart, lungs, kidneys, brain, skin, eyes and/or gastrointestinal organs. MIS can affect children (MIS-C) and adults (MIS-A). Research has found that inflammation and cell damage can reach even the testicles in men. Long Covid patients are found to have sustained inflammation and activation of the immune response for at least 8 months after initial infection. If you suffer from Long Covid or dysregulated inflammation, talk to your healthcare practitioner on ways to lower unwanted inflammation naturally and to promote an optimal inflammation response.
  4. It’s the terrain!” Researchers have discovered that people with certain pre-existing conditions have a higher risk of developing Long Covid. How healthy our body (“terrain”) is will determine how well it will fight off Covid- and the next pathogen. Click here to read more on how to support your immune system. As part of the Coronavirus COVID-19 pandemic guidance, the Scottish government has recommended that people start getting a daily dose of vitamin D. Click here to read the role of vitamin D in immune function.

To those in Hong Kong, stay safe and take care. We will get through this together.

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