Since the early days of the epidemic, brain fog has emerged as the most common health problem after COVID-19.
Brain fog is a colloquial term that describes a state of mental sluggishness or lack of clarity and dullness that makes it difficult to concentrate, remember things and think clearly.
Fast-forward four years and now there is a lot of evidence that infection with SARS-CoV-2 – the virus that causes COVID-19 – can affect brain health in several ways.
In addition to brain fog, COVID-19 can lead to a series of complications, including headaches, seizures, strokes, sleep problems, and tremors and nerve weakness, as well as mental health concerns.
A large and growing body of evidence gathered during the pandemic explains the many ways in which COVID-19 leaves an indelible mark on the brain. But the exact mechanisms of the virus are still being elucidated, and medical treatments are not available.
Now, two 2024 studies published in the New England Journal of Medicine further shed light on the profound impact of CCIDID-19 on cognitive health.
I am a medical scientist, and I have devoted myself to studying chronic COVID since the patient first reported the disease – even before the term “chronic COVID” was coined. I testified before the US Senate as an expert witness on the long COVID and published extensively on the subject.
How does COVID-19 leave a mark on the brain
Here are some of the most important studies to date documenting how COVID-19 affects brain health:
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A large epidemiological study showed that people who had CCIDID-19 were at an increased risk of cognitive deficits, such as memory problems.
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Imaging studies performed in humans before and after infection with CCID-19 show a decrease in brain volume and changes in the brain after infection.
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A study of people with mild to moderate COVID-19 showed long-term brain inflammation and changes consistent with seven years of brain aging.
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Severe COVID-19 that requires hospitalization or intensive care can cause cognitive impairment and other brain damage equivalent to 20 years of aging.
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Laboratory experiments in human and mouse brain organoids designed to mimic changes in the human brain have shown that the SARS-CoV-2 virus causes fusion of brain cells. This effectively short-circuits the brain’s electrical activity and disrupts function.
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Autopsy studies of people who had severe COVID-19 but died months later from other causes showed that the virus was still present in the brain. This provides evidence that contrary to its name, SARS-CoV-2 is not only a respiratory virus, but can also enter the brain in some people. But whether the persistence of infection in brain tissue is driving some of the brain problems seen in people who have had COVID-19 is still unclear.
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Studies show that even if the virus is mild and confined to the lungs, it can cause inflammation in the brain by affecting the ability of brain cells to regenerate.
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COVID-19 can also damage the blood brain barrier, the shield that protects the nervous system – which is the control and command center of our bodies – causing it to “collapse.” Studies using imaging to examine the brains of people hospitalized with CCIDID-19 have shown disruption or leakage of the blood brain barrier in those who experienced brain fog.
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The first large-scale analysis collecting data from 11 studies including about 1 million people with COVID-19 and more than 6 million people without the virus showed that COVID-19 increased the risk of developing dementia in people over 60 years of age.
It drops in IQ
Recently, a new study published in the New England Journal of Medicine examined cognitive abilities such as memory, planning and spatial reasoning in approximately 113,000 people who previously had COVID-113. The researchers found that those who were infected had significant deficits in memory and executive functioning.
This decrease was observed among those infected in the first phase of the epidemic and those infected when the delta and omicron variants were high. These findings suggest that the risk of cognitive decline did not decrease as the virus evolved from the ancestral to the micron.
In the same study, those who were mild and recovered from COVID-19 showed cognitive decline equivalent to a loss of three IQ points. In comparison, those with unremedied persistent symptoms, such as persistent shortness of breath or fatigue, had a loss of six points in IQ. Those who had been admitted to the intensive care unit for CCIDID-19 lost nine points in IQ. Re-infection resulted in a loss of two points in IQ, compared to no re-infection.
Usually the average IQ is about 100. An IQ above 130 indicates a highly gifted individual, while an IQ below 70 usually indicates a level of intellectual disability that may require significant social support.
To put the findings of the New England Journal of Medicine study into perspective, I estimate that a three-point downward shift in IQ would increase the number of adults in the United States with an IQ of less than 70 from 4.7 million to 7.5 million — an increase of 2.8 million adults with mild cognitive impairment. it needs special support in the community.
Another study in the same issue of the New England Journal of Medicine included more than 100,000 Norwegians between March 2020 and April 2023. It documented worse memory function at several times up to 36 months following a positive test for SARS-CoV-2.
Analyzing meaning
Taken together, these studies show that COVID-19 poses a serious risk to brain health, even in mild cases, and the effects are now being shown in the general population.
The latest US Current Population Survey showed that after the start of the CCIDID-19 epidemic, an additional one million working-age Americans said they have “greater difficulty” remembering, concentrating or making decisions than at any time in the past 15 years. . Even more disturbing, this was mostly driven by young adults between the ages of 18 to 44.
Data from the European Union shows a similar trend – in 2022, 15% of people in the EU reported memory and concentration issues.
Looking ahead, it will be important to know who is at risk. A better understanding is also needed of how these trends may affect the educational attainment of children and young adults and the economic development of working-age adults. And how these changes will influence the epidemiology of dementia and Alzheimer’s disease is unclear.
A growing body of research now confirms that COVID-19 should be considered a virus with significant effects on the brain. The consequences are far-reaching, from people experiencing mental health problems to the potential impact on population and the economy.
Unraveling the truth behind these cognitive impairments, including brain fog, will require years if not decades of collaborative effort by researchers around the world. And unfortunately, almost everyone is a test case in this unprecedented world.
This article is published from The Conversation, a non-profit, independent news organization that brings you facts and reliable analysis to help you understand our complex world. Written by: Ziyad Al-Aly, Washington University in St
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Ziyad Al-Aly receives funding from the US Department of Veterans Affairs.