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COVID-19 takes a toll on cognitive function

A man doing a crossword puzzle.

March 21, 2024—Since the start of the pandemic, scientists have learned a lot about COVID-19 and its long-term effects. One key discovery: COVID-19 is not just a respiratory infection. It affects organs throughout the body, including the brain.

In fact, cognitive problems—trouble thinking, concentrating or remembering, commonly called "brain fog"—is one of the most common symptoms of long COVID-19, according to the American Heart Association.

But even people whose COVID-19 symptoms resolved quickly—within four weeks—may experience changes in thinking and memory, according to a recent study published in the New England Journal of Medicine.

COVID-19 affects cognition

To discover how COVID-19 affects cognition, researchers studied 112,964 adults from England. Some participants had not had COVID-19. Others had it but recovered quickly, in less than four weeks. Others had symptoms for 12 weeks or longer.

The study participants completed a variety of thinking tests on their smartphones or computers. The tests gauged how quickly and correctly people did tasks related to memory, reasoning and planning. Study subjects were asked to recall words, understand analogies and do spatial planning exercises.

When the researchers compared participants who had COVID-19 to those who did not, they found that:

  • People who recovered from COVID-19 symptoms in less than four weeks had a decline in cognitive function equivalent to losing three IQ points.
  • People who were still having COVID-19 symptoms for 12 weeks or more lost the equivalent of six IQ points.
  • People who had been infected by later virus variants scored better than those who had been infected with early variants.
  • People who spent time in intensive care units experienced the biggest cognitive decline, around nine IQ points.
  • Those who got two or more vaccinations before getting sick with COVID-19 experienced less cognitive decline than people who hadn't gotten their vaccinations.

More research is needed to see if these changes improve over time.

Protect yourself from COVID-19

People who were hospitalized with COVID-19 had more trouble with thinking and memory than those whose cases were mild. Staying up-to-date on COVID-19 vaccines and boosters helps prevent serious illness.

If you do have lingering symptoms after an infection, talk to your doctor about long COVID-19 and what you can do to feel better.


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