August 21, 2024, 10:17 p.m. | Reading time: 6 minutes
Even though the coronavirus plays an increasingly smaller role in our perception, infections with new variants still occur. And this can continue to lead to long-term consequences, known as Long Covid. Now researchers have deciphered why this happens and what happens in the brain. FITBOOK author Martin Lewicki explains the study.
Especially now in summer, the number of corona infections has risen slightly again. At the end of May 2024, the 7-day incidence was just one laboratory-confirmed case per 100,000 inhabitants in Germany.1 From then on, the number of infections rose to up to six laboratory-confirmed cases at the end of July. Because very few people are getting tested for corona, the number of unreported cases is likely to be significantly higher. And with that, the risk of long-term Covid disease also increases. Researchers have now discovered which changes Covid-19 can trigger in the brain, which in turn can lead to long-term Covid.
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The most common Long Covid symptoms
Studies have already identified the most common long-term consequences of a corona infection, as FITBOOK reported in an earlier article. These include the following symptoms:
- Loss of smell and/or taste
- Discomfort after physical exertion
- Chronic cough
- Brain Fog
- Excessive thirst
- Heart palpitations
- Chest pain
- Exhaustion (Fatigue)
- Problems with libido / problems during sex
- Dizziness
- Gastrointestinal complaints
- Motor changes and complaints
Researchers conducted experiments on rats
American scientists from the University of Colorado wanted to find out how the long-Covid symptoms and changes in the brain come about.2 To do this, they conducted experiments on rats that were injected with special antigens of the Covid-19 virus.
As the researchers report, previous studies have shown that these immune-stimulating antigens, which are secreted by the Covid-19 virus, remain in the bloodstream of corona patients for up to a year after infection. They have also been detected in the brains of corona patients who have died.
To study how these antigens affect the brain and nervous system, they injected such an antigen (S1) into the spinal fluid of rats. They then compared the blood and hormone levels with a control group of rats that were not injected with the antigen.
Covid-19 antigen lowers cortisol levels in the brain
A measurement of the hormone levels showed that after just seven days, the level of the cortisol-like hormone corticosterone in the hippocampus of the brain had fallen by 31 percent. This is the region of the brain responsible for memory, decision-making and learning. After nine days, the levels in the rats that were injected with the Covid-19 antigen had fallen by 37 percent.
“Nine days is a long time in the lifespan of a rat,” said Dr. Matthew Frank, lead author of the study, in a press release.3 Compared to humans, this is a long period of time, considering that rats live an average of two to three years.
What role does cortisol play in our body?
Cortisol is an important hormone that many people will certainly know as the stress hormone. It is released in the body in stressful situations and makes us wide awake, especially in dangerous situations. It is also important for regulating our sleep and fat metabolism. As the researchers emphasize in the study, it is also an important anti-inflammatory that regulates the immune response to infections.
Previous studies have shown that many patients with Long Covid have low cortisol levels.4 People who suffer from chronic fatigue also have low cortisol levels. Clear evidence that low cortisol levels can have negative consequences and promote inflammation in the body. “Cortisol has so many useful properties that lowering cortisol levels can have a number of negative consequences,” emphasizes study researcher Dr. Matthew Frank.
Low cortisol levels make the brain more susceptible to inflammation
To find out how the low cortisol level affects immune stress, the researchers conducted another experiment with the rats. They gave both groups of rats a weakened bacteria that led to a mild infection in the body.
When analyzing the biological data, they found that the group of rats that had previously been exposed to the Covid-19 antigen reacted much more strongly to the infection. They showed pronounced changes in eating, drinking, core body temperature and heart rate. In addition, there were more severe inflammatory processes in the brain and nervous system compared to the rats that were not exposed to the Covid-19 antigen.
“For the first time, we were able to show that exposure to antigens left behind by the virus can actually alter the immune response in the brain in such a way that it overreacts to subsequent stressors or infections,” explains Dr. Frank.
More on the topic
Worrying study: Living with Long Covid can be worse than living with cancer
Study by Columbia University Why does the loss of smell last so long after a corona infection?
Corona long-term effects study identifies four factors that increase the risk of Long Covid
How do I know if I have Long Covid?
Long Covid occurs when health problems persist for at least four weeks after a Covid-19 infection. One of the most frequently reported symptoms is severe tiredness and exhaustion. This makes even everyday tasks such as climbing stairs or preparing something to eat and drink a challenge, as the Health Knowledge Foundation reports.5 In addition, breathing difficulties, muscle pain, and concentration and memory problems often occur.
What you can do to combat Long Covid symptoms is explained by the Health Knowledge Foundation in its Guide Living with Long Covid listed.
