This text is taken from our newsletter “Coronavirus mail” of May 30, 2022. To subscribe, click here.
Researchers have been racking their brains for two years to understand the consequences of COVID-19 on the brain. English researchers have demonstrated that a severe form of COVID-19 causes “cognitive loss similar on average to that suffered with 20 years of aging, between 50 and 70 years”.
This recent study joins an ever-growing scientific body proving the deleterious effects of the disease on the brain.
A team of researchers from Université Laval also took part in this scientific debate. She demonstrated that even in asymptomatic people, COVID-19 reduces gray matter by an average of at least 0.2%.
“It’s huge for humans, this small difference,” confirms Ayman ElAli, brain disease specialist and co-author of the study. “These are observations usually made in degenerative diseases. »
Should this result in reduced cognitive abilities? Hard to say. “Human cognition is very complex. There are regions of the brain [qui peuvent être touchées] which control more the memory, others more the executive tasks”, he explains.
Thus, the brain shrinks after an infection (“it’s obvious”), but the consequences on the psyche remain to be defined.
These “microdamages” to the brain can take years to snowball and cause serious damage to cognition in those infected, ElAli said.
“Age is one of the factors of brain degradation. Cumulation [des problèmes cérébraux] will appear over time. It will be necessary to wait 5 to 10 years before seeing an effect. I’m not an alarmist, but I think we’re going to see worrying things in that regard. »
In other words, people prone to dementia or Alzheimer’s, for example, could see their risk of suffering from it increase.
The fault of inflammation
There are several avenues to explain the brain damage caused by COVID-19 – yet a respiratory disease.
One of the most promising leads is that of the inflammation caused by the coronavirus.
“Blood vessels in the brain have been found to burst or malfunction or clog sometimes,” says ElAli. It’s a clue that there’s something going on with the ships. The brain is one of the organs most affected by vascular problems. »
Another avenue suggests that the inactivation of cells in the nose by the virus leads to the destruction of part of the brain. “When you don’t use a function, a limb, say, the part of the brain that uses that function gets a little lazy” and declines, he says of brain damage.