(ORDO NEWS) — We all know that COVID-19 can lead to lingering fatigue and brain fog. But one of the most rigorous studies to date on the long-term cognitive effects of severe infection has come up with some rather troubling results.
In a study that compared 46 patients with severe COVID-19 to 460 controls, researchers found that the mental consequences of severe COVID-19 after six months could be equivalent to 20 years of aging – from 50 to 70 years – or loss of 10 IQ points.
Specific mental changes also differed from those observed in dementia praecox or general aging.
Cognitive impairment is characteristic of a wide range of neurological diseases, including dementia, and even normal aging, but the patterns we observe – the cognitive “fingerprints” of COVID-19 – differ from all these diseases,” says neuroscientist David Menon from the University of Cambridge in the UK. senior author of the study.
The new work does not aim to alarm the many of us who have already contracted COVID, but instead takes a closer look at how severe cognitive changes are after severe cases of infection so that we can understand how to mitigate them.
“Tens of thousands of people went through intensive care with COVID-19 in England alone, and many others were very sick but did not get to the hospital,” says lead researcher and cognitive scientist Adam Hampshire from Imperial College London.
“This means that a large number of people are still experiencing cognition problems many months later. We urgently need to see what can be done to help these people.”
The experiment involved 46 people who presented to Addenbrooke’s Hospital in Cambridge as a result of COVID-19 between March and July 2020. Sixteen of them were placed on mechanical ventilation during their stay in the hospital.
On average, six months after infection, the researchers followed them with a testing tool called Cognitron to see how they fared in areas such as memory, attention, thinking, as well as anxiety, depression and post-traumatic stress disorder.
The researchers did not have test results from before these people got COVID to compare. Instead, what they did was compare their results with those of a control group of 460 people.
These results were then compared to see how much they deviated from the expected figures for their age and demographics, based on 66,008 members of the general public.
The results showed that people who experienced severe COVID were less accurate and had slower reaction times than people in general.
The magnitude of cognitive loss was similar to the effects of aging between the ages of 50 and 70 – and equivalent to a loss of 10 IQ points.
Accuracy in verbal analogy tasks when people are asked to find similarities between words has suffered the most. This reflects anecdotal reports that people have difficulty finding the right word after an infection and feel like their brains are in slow motion.
Interestingly, even though patients reported varying levels of fatigue and depression, the severity of the initial infection, rather than the patient’s current mental health, best predicted cognitive outcome, the team found.
“These results suggest that while both fatigue and mental health are prominent chronic [consequences] of COVID-19, their severity is likely to be somewhat independent of observed cognitive impairment,” the researchers write in their paper.
Somewhat good news is that there were some signs of recovery on follow-up – but it was gradual at best.
“We followed some patients ten months after an acute infection, so we could see a very slow improvement,” says Menon.
“Although it wasn’t statistically significant, it’s at least a move in the right direction, but it’s possible that some of these people will never fully recover.”
This study only looked at extreme hospital admissions, but there are many other studies showing that even “mild” cases can cause similar cognitive outcomes.
It is still not fully understood why and how the SARS-CoV-2 virus causes this cognitive decline.
Previous research has shown that during severe COVID, the brain reduces glucose uptake in the fronto-parietal network, which is involved in attention, problem solving and working memory. It is also known that the virus can directly affect the brain.
But the researchers suggest that the likely culprit is not a direct infection, but a combination of factors, including decreased oxygen or blood supply to the brain, vascular clotting, and microscopic bleeding.
There is also growing evidence that the body’s own immune and inflammatory response can have a significant impact on the brain.
“Future work will focus on correlating these cognitive impairments with underlying neuronal pathologies and inflammatory biomarkers, as well as longitudinally tracking recovery in the chronic phase,” the researchers wrote.
In the meantime, take comfort in the fact that if you’re still feeling sluggish and hazy months after recovering from COVID-19, you’re probably not alone.
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