They show that the new results from the Corona study at Oslo University Hospital (OUS).
The findings have been published in the scientific journal New England Journal of Medicine.
Den store coronastudien
Shortly after the pandemic hit Norway, researchers at OUS started the so-called Corona Study. It was supposed to deal with how things have gone with us after most of us have been infected by covid-19.
It is one of Norway’s largest cohort studies with around 200,000 participants.
One of the advantages of the Corona Study is that it was launched early in the pandemic, before the virus had gained a proper foothold in the Norwegian population. The researchers thus have good information about health and behavior both before and after covid-19.
As part of this study, the researchers asked the participants to take a memory test.
Poor memory in everyday life
It turned out that those who have had covid-19 struggled more with their memory after covid-19 than before they got sick. They also struggled more than those who had never tested positive for covid-19.
The researchers investigated what is called everyday memory.
One of the questions was how often do you experience having something on your tongue, but which you are unable to say.
Or that you repeat something you have already said.
The participants graded their answers from zero to four – from rarely to often.
The questions were part of a so-called validated questionnaire, says Arne Søraas, one of the researchers behind the new study. This means that the form is approved in the research environment and is often used in this type of research.
– We know that if you score poorly on the form, you can have memory problems that affect your quality of life, says Søraas, who is a doctor and researcher at Oslo University Hospital.
Infected several times
Many people in Norway have been infected with covid-19 not just once, but several times since spring 2020. Does this have anything to do with the memory problems?
The researchers do not yet have a correct answer to that.
– It will be something we have to look at further, says Sonja Brunvoll, also one of the researchers behind the study.
Because how big is the risk that you will experience memory problems if you are reinfected with covid-19?
If you haven’t had memory problems after the first time you have covid-19 or the second time, how about the third and fourth time?
Søraas talks about other studies, including reports from Canada, where it may appear that the problems with memory increase each time you get the disease.
– So even if you have had covid-19 four times, it is not certain that you are safe the fifth time, so to speak, says Søraas.
He still hopes they will see a so-called flattening curve as one has had the virus several times. But since it’s a brand new virus, they don’t know yet.
Which variant causes the most problems?
Those who got covid-19 at the very beginning were infected with the first Alfa variant. It caused more serious disease than some of the other variants that came later, and those who got sick were also unvaccinated. It is these researchers who have had the longest follow-up, up to three years after covid-19.
The largest group of participants that Brunvoll and his colleagues have followed were infected with the omikron variant. It caused less severe disease, and most people were vaccinated at this time. These took the memory test up to one year after they had the disease.
– It will be very important to follow up on these going forward, says Brunvoll.
The researchers want an answer to whether these also score as poorly three years later, like those who were infected by the first variant.
15 percent experienced memory problems
The study of Ellingjord-Dale, Brunvoll and Søraas and includes 112,000 participants.
– One of the strengths of this study is that we have so many participants that we have followed for up to three years, says Merete Ellingjord-Dale.
Previous scientific articles from the Corona Study show that ten to 15 per cent of those who have had covid-19 report concentration and memory problems.
In this publication, the average score for those who have had covid-19 is between 0.7 and 0.8, where four is the maximum bad memory.
It is important to point out that this is an average score, says Ellingfjord-Dale.
– Behind the numbers hide participants who score higher than that, she says.
– For these, memory problems and concentration difficulties can affect the quality of life, she says.
– So for those concerned, this is serious.
Vacancies
Further follow-up
The researchers say they will monitor whether the problems persist or whether they gradually decrease. So far, they have shown that the memory problems persist three years after the first positive test.
– If this continues, there are big financial costs for society, says Ellingjord-Dale.
Søraas thinks it is worrying that the memory problems last so long and that it was a little surprising that the curve did not start to go down after three years.
– At first it was thought that covid-19 was a pure respiratory infection, then it was realized that it had after-effects. Now it turns out that the after-effects, such as memory problems, can last up to three years. They have lasted as long as we have measured, so it may be that they actually last longer, he says.
– If you get four million people infected every year in Norway, it is clearly serious, he says.
Worst for younger women
Both age and gender influenced how the participants did on the memory tests.
Women reported more memory problems than men.
– It is not unusual for there to be gender differences in diseases, says Søraas.
Precisely in this case, it may have something to do with the infection dose. Women who work in healthcare or with children may have been infected with many viruses at once, explains Søraas.
– And we see that the sicker you were with covid-19 in the acute phase, the more memory problems you can expect to experience later, says Søraas.
Women are also more susceptible to autoimmune diseases such as Sjøgren’s syndrome, multiple sclerosis and celiac disease.
– One of the theories about long covid is that it is about auto-immunity, says Søraas.
Internet questionnaire excludes very old participants
More memory problems were reported among the younger than the older.
This could be about the sample in the study itself, explains Brunvoll.
– This is probably mostly about who the older people in the study actually are. The participants, for example, had to log in to the form with their BankID online, so it is probably the very freshest who take part. Therefore, we do not think that we can say that younger people have greater problems with memory, says Brunvoll.
The minimum age to participate in the Corona Study is 18, and the average age is 49.
Reference:
Sonja H. Brunvoll, Merete Ellingjord-Dale and Arne Søraas: Prospective Memory Assessment before and after
Covid-19. New
England Journal of Medicine. Februar 2024.
2024-02-28 22:00:00
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