People who require hospitalization for COVID-19 develop persistent cognitive problems similar to what might be expected if they were 20 years old.
That’s according to a new UK study published online April 28 in the journal eClinicalMedicine. The research is somewhat limited in that it included fewer than 50 COVID-19 patients, but it adds to the large body of research already suggesting that coronavirus infection leaves a lasting impact on the brain.
For example, a 2021 study showed that many long-distance COVID carriers — those who experience multiple symptoms for weeks or months after initial infection — reported experiencing multiple brain-related symptoms, including “brain fog,” or difficulty to think, headache and loss of sense of smell or taste, Live Science previously reported. These persistent symptoms were not exclusive to those who developed severe COVID-19 infections, but also affected those who experienced only mild illness, according to the study.
More recently, a large study found distinctive brain shrinkage patterns in hundreds of people who previously contracted COVID-19, and it’s possible that this abnormal atrophy contributes to the cognitive deficits seen in patients, the authors suggested.
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The new UK study focused on severe cases of COVID-19 that required hospitalization and assessed how those patients fared on cognitive tests six to 10 months later, compared to people who never contracted COVID-19. (The study did not include cognitive test scores before the patients contracted COVID-19, which is another limitation of the research.)
The study included 46 people who received critical care for COVID-19 at Addenbrooke’s Hospital in Cambridge, UK, between March 10 and July 31, 2020; the patients were between 28 and 83 years old. Sixteen of these patients were placed on ventilators during their stays, and of these, 14 required medical support for multiple failing organs. The researchers compared these 46 patients with 460 people of the same ages and demographics who had not previously contracted COVID-19.
All participants completed eight cognitive tests through the Cognitron platform, an assessment platform developed by Imperial College London. Overall, compared to the control group, COVID-19 patients showed a “consistent pattern” of reduced accuracy and slower processing time on tests, although the degree of imprecision and slowness varied between tasks.
Compared to controls, the COVID-19 group showed the most significant deficits on verbal analogy tasks, in which they were asked to complete analogies such as “‘Up’ is to ‘Down’ as ‘Over’ is to ‘Under'”, for example. They also showed lower accuracy and speed in a spatial task called “2D manipulation,” in which they were asked to manipulate a 2D shape in their mind to solve a puzzle.
On average, the level of cognitive decline among controls and COVID-19 patients was “similar in scale to normal age-related cognitive decline among individuals in their 70s compared to individuals in their 50s,” the authors wrote in their report. . The severity of this decline varied between individual patients depending on the severity of their initial infection, meaning that it was worse among those who required ventilation and multiple organ support.
The team found no notable differences between patients evaluated six months after their hospital stay and those evaluated 10 months later, although the 10-month group did slightly better. “We conclude that any cognitive recovery is likely to be slow at best,” the authors wrote. “It is also important to keep in mind that cognitive recovery trajectories may vary among individuals depending on disease severity and neurological or psychological underpinnings, which are likely to be complex.”
These open questions will be addressed in future studies.
Researchers hope that such studies will allow them to understand the mechanisms behind cognitive decline, and perhaps prevent or treat it, studies senior author David Menon, a professor at the University of Cambridge, he told The Guardian.
Originally published on Live Science.