People that have suffered severe cases of COVID-19 may experience mental decline equal to the brain aging by a decade, according to a new study released this month.
Researchers from the U.K. analyzed the test data of over 84,000 participants who took the Great British Intelligence Test and were suspected or confirmed to have COVID-19.
The study, which has not yet been peer-reviewed, found that people who had recovered from severe cases of the disease exhibited “significant cognitive deficit” after controlling for other factors such as age, gender and pre-existing medical conditions.
Some deficits were of “substantial effect size,” the researchers found, specifically among those who had been hospitalized and those who had mild cases and reported no difficulty breathing. However, among those who ended up on a ventilator, the deficits were “equivalent to the average 10-year decline in global performance between the ages of 20 to 70.”
The cognitive decline could be the result of other health events that are thought to be associated with COVID-19 such as stoke, inflammatory syndrome and micro bleeds, according to the study.
COVID-19 is a disease that can have critical impacts on the upper respiratory system, leading patients with severe cases to require supplemental oxygen. As a result, researchers in the study have also hypothesized that hypoxia in the brain could also lead to cognitive decline.
However, they write, “it is yet to be established whether COVID-19 infection is associated with cognitive impairment at the population level; and if so, how this differs with respiratory symptom severity and relatedly, hospitalisation status. Measuring such associations is challenging.”
In all, the scientists said that their findings “align with the view that there are chronic cognitive consequences of having COVID-19. Individuals who recovered from suspected or confirmed COVID-19 perform worse on cognitive tests in multiple domains than would be expected given their detailed age and demographic profiles.”
The researchers said their study should be a “clarion call” for more research into the basis cognitive deficits in recovered COVID-19 patients.
Some scientists say that the study’s results should be viewed cautiously.
Derek Hill, a professor of medical imaging science at University College London, told Reuters that the study did not compare before and after scores of participants, and that a large number of them only self-reported having the virus without a positive test.
“Overall (this is) an intriguing but inconclusive piece of research into the effect of COVID on the brain,” Hill told Reuters. “As researchers seek to better understand the long term impact of COVID, it will be important to further investigate the extent to which cognition is impacted in the weeks and months after the infection, and whether permanent damage to brain function results in some people.”