A long period of Covid can lead to measurable cognitive decline, research shows

Long Covid can lead to measurable cognitive decline, especially in the ability to remember, reason and plan new study suggests.

Cognitive tests of nearly 113,000 people in England found that people with persistent post-Covid symptoms scored the equivalent of 6 IQ points lower than people who had never been infected with the coronavirus, according to the study published Wednesday in The New England Journal of Medicine was published. .

People who had been infected and no longer had symptoms also scored slightly lower than people who had never been infected, by the equivalent of 3 IQ points, even if they had only been ill for a short time.

The differences in cognitive scores were relatively small, and neurological experts cautioned that the results did not imply that catching the coronavirus or developing long Covid-19 caused serious deficits in thinking and functioning. But the experts said the findings are important because they provide numerical evidence for the brain fog, focus and memory problems that many people with long Covid-19 suffer.

“These emerging and converging findings overall emphasize that there is indeed cognitive impairment in long Covid survivors — it is a real phenomenon,” said James C. Jackson, a neuropsychologist at Vanderbilt Medical Center, who was not involved in the study was involved.

He and other experts noted that the results were consistent with smaller studies that have found signs of cognitive impairment.

The new study also found reasons for optimism, suggesting that as people’s long Covid symptoms subside, associated cognitive impairment could also emerge: people who experienced long Covid symptoms for months and eventually recovered had cognitive scores that were similar were with those who had experienced a quick recovery. , the study showed.

On a typical IQ scale, people with a score of 85 to 115 are considered of average intelligence. The standard variation is about 15 points, so a shift of 3 points is typically not considered significant and a shift of even 6 points may be inconsequential, experts said.

“The question is: are people able to function in their routine capacity, whatever they are doing? And this isn’t really answered by 3 points more or less,” said Dr. Igor Koralnik, chief of neuroinfectious diseases and global neurology at Northwestern Medicine in Chicago, who was not involved in the study.

He added: “The determination of X points on an IQ scale is less important than people’s perception of their cognitive problems.”

Yet Dr Jackson, the author of a book on long Covid-19 called ‘Clearing the Fog’, said that while cognitive tests like those in the study ‘identify relatively mild deficits’, even subtle difficulties could matter for some people . For example, he said, “If you’re an engineer and you have a slight decline in executive functioning, that’s a problem.”

The study, led by researchers at Imperial College London, involved 112,964 adults who completed an online cognitive assessment in the last five months of 2022. About 46,000 of them, or 41 percent, said they had never had Covid. Another 46,000 people infected with the coronavirus said their illness had lasted less than four weeks.

About 3,200 people had post-Covid symptoms that lasted four to 12 weeks after their infection, and about 3,900 people had symptoms after 12 weeks, including some that lasted a year or more. Of those, 2,580 people still had post-Covid symptoms when they took the cognitive test.

The researchers noted that they relied on self-reported symptoms, rather than long Covid-19 diagnoses, and that the demands of taking a cognitive test may have prevented study participants from had the most severe limitations.