(Montreal) Infection with SARS-CoV-2, the virus responsible for COVID-19, can lead to long-term cognitive deficit which, in some cases, may correspond to the loss of three intelligence quotient points, prevents a new study published by the prestigious New England Journal of Medicine.
The cognitive deficit was particularly pronounced in patients infected when the original strain of the virus or the B.1.1.7 variant. were dominant.
“Even people who have had a diagnosis of long COVID and who subsequently returned to their baseline state, supposedly there still remains this little background of deficiency, of cognitive impairment, which resembles those who had a faster resolution after four to twelve weeks, so that’s interesting,” commented Dr. Emilia Falcone, who is leading her own work to unravel the mysteries of long COVID at the Montreal Clinical Research Institute.
The authors of the study base their results on the responses provided by some 115,000 Britons to an online questionnaire consisting of eight cognitive tasks.
They found that participants whose symptoms had resolved in less than four weeks, or at most in less than twelve weeks, presented small cognitive deficits comparable to those of participants who had never been infected with the virus or whose it was unclear whether they had been infected.
In contrast, greater cognitive deficits were measured in participants whose symptoms persisted. Hospitalization, particularly in the intensive care unit, has also been associated with more pronounced cognitive deficit.
“But we must not forget that there are aspects of being in intensive care that can have a long-term impact on patients,” recalled Dr. Falcone. Ending up in intensive care adds to the impact of the infection. »
Patients who were vaccinated at least twice and who were minimally affected by subsequent SARS-CoV-2 infections had a modest cognitive advantage.
The authors note that the greater cognitive deficit associated with infection at the start of the pandemic corresponds to a period when the health care system was overwhelmed, when effective therapies were not yet available, and when the likelihood of hospitalization was higher.
The study published by NEJM is not the only one to shed new light on how the COVID virus appears to interfere with proper brain function.
Detailed work in Nature Neuroscience in mid-February indicates that the virus seems to make the blood-brain barrier which normally protects the brain from intruders more permeable. Damage to this barrier appears particularly significant in long-COVID patients who report what is now described as “brain fog.”
Another study published by Nature Neuroscience suggests that inflammation caused by SARS-CoV-2 could lead to an immune response in certain regions of the brain in the early days of infection, which could cause symptoms neurological such as loss of smell.
“The more it progresses, the more we begin to have pieces of the puzzle that complete the picture a little, that there is an attack [au cerveau], concluded Dr. Falcone. We see it from different angles. Every day we have a new revelation. »