AP Biology class blog for discussing current research in Biology

Is Brain Fog Becoming Clear?

Has anyone ever tried to talk to you the second after you woke up?  It’s almost impossible to comprehend what they’re saying within those first ten seconds that you’re awake, right? Now imagine if those ten seconds lasted weeks, months, or even years, and you’ll be imagining the life of someone with post-COVID-19 brain fog.

“Brain fog,” is a feeling of confusion, inability to concentrate, fatigue, and overall “cloudy” mindedness that is a common residual symptom of the SARS-CoV-2 virus, affecting about forty percent of people who experience “long COVID” symptoms.  Although unable to be detected through any sort of medical examination or test, post-COVID brain fog can have an overwhelming presence, causing people to be unable to work and frequently lasting for over a year.  However, because brain fog only became an extremely common complaint of patients since the COVID-19 pandemic started, scientists know very little about the symptom.

SARS-CoV-2 without background

In an attempt to discover more, scientists at Karolinska Institute, led by Carl Sellgren, researched how the SARS-CoV-2 virus affects the brain by infecting organoid brain cells with SARS-CoV-2.  The experiment revealed that the virus caused neuron synapses to be destroyed at an unnaturally high rate.  As we learned in AP Biology, neurons are signaling cells that exist throughout the body but make up most of the brain.  Neurons are not actually connected- a small gap, called a synapse, between the end of one neuron (or the presynaptic membrane) and the start of the next (called the postsynaptic membrane) separates the two cells.  Neurons signal each other by sending small particles called neurotransmitters across the synapse and into the next cell.  Another common brain cell is microglia, which are immune system cells that dispose of dead cells and repair synapses.  Microglia also destroy synapses, or connections between neurons, when they are no longer needed.  

Complete neuron cell diagram en

Sellgren’s study revealed that SARS-CoV-2 causes microglia in the brain to amplify the rate at which they destroy synapses, preventing many neurons from being able to make connections with other neurons.  Assuming that a full human brain would respond the same way as brain organoids, this discovery explains why long-COVID patients with brain fog experience difficulty thinking.  Amplified microglia activity is also associated with aging, which further supports the results of Sellgren’s experiment because people oftentimes become more forgetful with age.

With this new discovery to open the gates to more knowledge, scientists can begin to understand post-COVID brain fog more deeply and potentially hope for treatment for this symptom that affects the lives of thousands of people.

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1 Comment

  1. jouleian

    This important research on the connection between SARS-CoV-2 and brain fog was very interesting. It’s alarming to learn about the high percentage of people who experience long-term symptoms such as confusion and difficulty concentrating after contracting the virus. The findings of the study at the Karolinska Institute on the destruction of neuron synapses and the role of microglia in this process offer valuable insights into the mechanisms behind post-COVID brain fog. It’s hopeful to consider that this research may pave the way for better understanding and treatment of this lingering symptom that impacts so many people. After reading your post, i read the article In this study, the researchers looked at the frequency of brain fog in a large group of patients who had survived COVID-19. They found that 7.2% of the patients reported experiencing brain fog as a long-term symptom of the disease, and that several factors were associated with an increased likelihood of experiencing brain fog. These included being female, having respiratory problems at the onset of the disease, and being admitted to the intensive care unit. These findings suggest that brain fog is a common long-term symptom of COVID-19, and that certain characteristics may increase a person’s risk of experiencing it.

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