We all know that COVID-19 can cause brain fog. The results of one of the most rigorous exams to date of the long-term cognitive impacts of severe infections are pretty unnerving.
The mental impacts of severe COVID-19 can be equivalent to aging 20 years, going from 50 to 70 years old, or losing 10 IQ points, according to a study.
Specific mental changes were not the same as those seen in early dementia or general aging.
The patterns we saw in COVID-19 were different from all of the other neurological disorders.
The new paper doesn't set out to alarm the many of us who have already had COVID, but instead investigate more closely how serious the cognitive changes are following severe cases of the infection, so we can begin to understand how to mitigate them.
Thousands of people have been through intensive care with COVID-19 in England alone and many more will have been very sick, but not admitted to hospital, according to Adam Hampshire from Imperial College London.
There are a lot of people who are still having problems with their cognitive abilities many months later. We need to look at what can be done to help these people.
The experiment involved 46 people who went to Addenbrooke's Hospital in Cambridge as a result of COVID-19 between March and July 2020. They were put on mechanical ventilation.
Researchers supervised them for six months after their infections to see how they were doing in areas such as memory, attention, reasoning, as well as anxiety, depression, and post-traumatic stress disorder.
The researchers did not have test results from before these individuals became ill. They compared their results against a matched control group of people.
The results were mapped to see how far they deviated from expected scores for their age and demographic, based on 66,008 members of the general public.
The results showed that people who survived severe COVID were less accurate and had slower response times.
The effects of aging between 50 and 70 years of age were equivalent to losing 10 IQ points.
In verbal analogy tasks, people are asked to find similarities between words. anecdotal reports suggest people are struggling to find the right word and feel like their brain is in slow motion.
The team found that the severity of the initial infection could be used to predict the cognitive outcome, even though patients reported varying levels of fatigue and depression.
The researchers write in their paper that fatigue and mental health are likely to be independent of cognitive deficits.
There were some signs of recovery, but it was gradual at best.
We followed some patients up as late as ten months after their infections, so they were able to see a slow improvement.
While this was not statistically significant, it is at least heading in the right direction, but it is very possible that some of these individuals will never fully recover.
This study only looked at the extreme end of hospitalized patients, but there are plenty of other studies showing that even mild cases can cause similar cognitive impacts.
Why the cognitive decline is caused by the SARS-CoV-2 virus is still not fully understood.
During severe COVID, the brain decreases the use of the frontoparietal network, which is involved in attention, problem solving, and working memory. The virus can affect the brain.
The likely culprit is a combination of factors, including reduced oxygen or blood supply to the brain.
There is mounting evidence that the immune and inflammatory response of the body may have an impact on the brain.
Future work will be focused on mapping these cognitive deficits to underlying neural pathologies and inflammatory biomarkers, and to longitudinally track recovery into the chronic phase.
If you are still feeling slow and foggy months after recovering from COVID-19, you are not alone.
The research has been published.
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