February 29, 2024 – People who recovered from COVID-19 showed a small loss in cognitive ability comparable to a 3-point IQ loss as much as a yr after recovery, while more severe cases of COVID experienced a much higher Loss of IQ was linked to brain function, a brand new study found.
The UK study found that individuals with more severe COVID cases that required treatment in a hospital's intensive care unit had cognitive deficits comparable to a 9-point drop in IQ.
The largest deficits on cognitive tasks were in memory, reasoning and executive function, said Adam Hampshire, Ph.D. from Imperial College London.
“People who had COVID-19 were both slower and less accurate at performing tasks that measure these skills,” Hampshire said.
The study was published online Wednesday in The New England Journal of Medicine.
Persistent brain fog
Cognitive symptoms after COVID are well-known, but whether cognitive deficits actually exist and the way long they persist stays unclear.
To investigate this, researchers invited 800,000 adults from the Real-Time Assessment of Community Transmission study Coronavirus transmission in England to conduct an eight-section online assessment of cognitive function.
In total, 141,583 participants began the cognitive battery by completing at the least one task and 112,964 accomplished all eight tasks.
Compared to uninfected adults, those that had COVID-19 and recovered had a small cognitive deficit, corresponding to a three-point loss in IQ, the researchers found.
Adults with persistent COVID-19 symptoms had an IQ lack of 6 points, and people admitted to the intensive care unit had an IQ lack of 9 points, the researchers report.
Major problems were present in adults infected with the unique virus variant or the B.1.1.7 variant early within the pandemic, while those that became infected later within the pandemic (e.g. within the Omicron period), showed less cognitive decline.
They also found that individuals who contracted COVID-19 after two or more vaccinations showed higher cognitive performance than those that had not been vaccinated.
The memory, reasoning and executive function tasks were amongst probably the most sensitive to COVID-19-related problems, and performance on these tasks varied depending on how long symptoms lasted and whether the person was hospitalized.
Hampshire said more research is required to find out whether cognitive deficits improve over time.
Major cognitive deficits likely?
These findings “are of concern and the broader implications require evaluation,” wrote Ziyad Al-Aly, MD, of Washington University School of Medicine in St. Louis, and Clifford Rosen, MD, of Tufts University School of Medicine in Boston an accompanying editorial.
In her view, some unanswered questions remain, including its potential The implications include a three-point loss in IQ and questions on whether COVID-19-related cognitive problems could mean a better risk of dementia later in life.
Commenting on the study, Jacqueline Becker, PhD, clinical neuropsychologist and assistant professor of medication on the Icahn School of Medicine at Mount Sinai, New York City, said “an important caveat” is that the study used a web based assessment tool for cognitive function The results should subsequently be viewed with caution.
“However, it is a large sample and the results are generally consistent with what we have seen in terms of cognitive deficits post-COVID,” Becker said.
It's likely that this study “underestimates” the extent of cognitive deficits found on neuropsychological testing, she said.
In a recent study, Becker and her colleagues examined the frequency of cognitive impairments in 740 people COVID-19 patients who’ve recovered and received outpatient, emergency room, or inpatient hospital care.
Using validated neuropsychological measures, they found a comparatively high frequency of cognitive impairment in patients several months after infection with COVID-19. Impairments in executive functions, processing speed, category competence, memory encoding, and recall were prevalent in hospitalized patients.