From the very early days of the pandemic, brain fog emerged as a significant health condition that many experience after COVID-19.
Brain fog is a colloquial term that describes a state of mental sluggishness or lack of clarity and haziness that makes it difficult to concentrate, remember things and think clearly.
Fast-forward four years and there is now abundant evidence that being infected with SARS-CoV-2 – the virus that causes COVID-19 – can affect brain health in many ways.
In addition to brain fog, COVID-19 can lead to an array of problems, including headaches, seizure disorders, strokes, sleep problems, and tingling and paralysis of the nerves, as well as several mental health disorders.
A large and growing body of evidence amassed throughout the pandemic details the many ways that COVID-19 leaves an indelible mark on the brain. But the specific pathways by which the virus does so are still being elucidated, and curative treatments are nonexistent.
Now, two new studies published in the New England Journal of Medicine shed further light on the profound toll of COVID-19 on cognitive health.
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- Large epidemiological analyses showed that people who had COVID-19 were at an increased risk of cognitive deficits, such as memory problems.
- Imaging studies done in people before and after their COVID-19 infections show shrinkage of brain volume and altered brain structure after infection.
- A study of people with mild to moderate COVID-19 showed significant prolonged inflammation of the brain and changes that are commensurate with seven years of brain aging.
- Severe COVID-19 that requires hospitalization or intensive care may result in cognitive deficits and other brain damage that are equivalent to 20 years of aging.
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Most recently, a new study published in the New England Journal of Medicine assessed cognitive abilities such as memory, planning and spatial reasoning in nearly 113,000 people who had previously had COVID-19. The researchers found that those who had been infected had significant deficits in memory and executive task performance.
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In the same study, those who had mild and resolved COVID-19 showed cognitive decline equivalent to a three-point loss of IQ. In comparison, those with unresolved persistent symptoms, such as people with persistent shortness of breath or fatigue, had a six-point loss in IQ. Those who had been admitted to the intensive care unit for COVID-19 had a nine-point loss in IQ. Reinfection with the virus contributed an additional two-point loss in IQ, as compared with no reinfection.
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Another study in the same issue of the New England Journal of Medicine involved more than 100,000 Norwegians between March 2020 and April 2023. It documented worse memory function at several time points up to 36 months following a positive SARS-CoV-2 test.
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 revealed at the population level.
A recent analysis of the U.S. Current Population Survey showed that after the start of the COVID-19 pandemic, an additional one million working-age Americans reported having “serious difficulty” remembering, concentrating or making decisions than at any time in the preceding 15 years. Most disconcertingly, this was mostly driven by younger adults between the ages of 18 to 44.
Data from the European Union shows a similar trend – in 2022, 15 percent of people in the EU reported memory and concentration issues.
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Robin Edgar
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