A non-peer-reviewed study of more than 84,000 people, led by Adam Hampshire, a doctor at Imperial College London, found that in some severe cases, coronavirus infection is linked to substantial cognitive deficits for months.
“Our analyses ... align with the view that there are chronic cognitive consequences of having COVID-19,” the researchers wrote in a report of their findings.
“People who had recovered, including those no longer reporting symptoms, exhibited significant cognitive deficits.”
Cognitive tests measure how well the brain performs tasks - such as remembering words or joining dots on a puzzle. Such tests are widely used to assess brain performance in diseases like Alzheimer’s, and can also help doctors assess temporary brain impairments.
The cognitive deficits were “of substantial effect size”, particularly among people who had been hospitalised with COVID-19, the researchers said, with the worst cases showing impacts “equivalent to the average 10-year decline in global performance between the ages of 20 to 70”.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
Scientists not directly involved with the study, however, said its results should be viewed with some caution.
Derek Hill, a professor of medical imaging science at University College London, also noted that the study’s findings could not be entirely reliable, since they did not compare before and after scores, and involved a large number of people who self-reported having had COVID-19, who had no positive test.
“Overall (this is) an intriguing but inconclusive piece of research into the effect of COVID on the brain,” Hill said.
“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.”Follow our full coverage of the coronavirus pandemic here.