Although the COVID-19 epidemic is no longer a global public health emergency, the chronic effects of acute viral infection still cause trouble for some people who have recovered.
Among them, the chronic impact of COVID-19 infection on cognitive function has attracted much attention.
On February 29 this year, the American medical journal "New England Journal of Medicine" published two large cohort studies from the UK and Norway, further confirming the correlation between COVID-19 infection and cognitive decline.
On March 1, the digital media "NEJM Medical Frontiers" jointly created by the "New England Journal of Medicine" and Jiahui Medical Research and Education Group invited Professor Cao Bin's team from the National Center for Respiratory Medicine to interpret these two studies.
Recently, Associate Researcher Gu Xiaoying and Dr. Zhang Hui, members of Professor Cao Bin's team, accepted an exclusive interview with reporters from China Youth Daily and China Youth Daily. They elaborated on the chronic impact of the new coronavirus infection on cognitive function and how to correctly understand and treat it. "Long COVID-19" expressed his opinion.
There is new evidence that acute COVID-19 infection causes cognitive decline
Gu Xiaoying introduced that the World Health Organization defines symptoms that are new or worsened 3 months after infection with the new coronavirus, last for no less than two months, and cannot be explained by other reasons as "long COVID-19."
The symptoms of "COVID-19" are diverse and can affect multiple organs and systems throughout the body, including fatigue, post-exercise discomfort, dyspnea, palpitation, abnormal smell and taste, etc. Cognitive problems (forgetfulness or inattention, etc.) are usually Known as “brain fog” - reporter’s note), it is also one of the symptoms of “COVID-19” that has received widespread attention.
Previous studies have shown that compared with research subjects who have fully recovered from COVID-19 infection, subjects with "long COVID-19" have slower cognitive responses.
People who have recovered from severe COVID-19 have a higher risk of developing cognitive dysfunction 1 year after infection than people who are not infected with COVID-19, and cognitive impairment still exists two years after infection.
The results of a cohort study from the United Kingdom published in the New England Journal of Medicine show that compared with people who were not infected or were not confirmed to be infected with the new coronavirus, there were fewer study subjects who recovered from symptoms within 4 weeks and 12 weeks after being infected with the new coronavirus. A similar mild decline in cognitive function was equivalent to a drop in IQ score of about 3 points; subjects who had not recovered from symptoms 12 weeks after infection had a more pronounced decline in cognitive function, equivalent to a drop in IQ score of about 6 points; those who were admitted to the intensive care unit Patients' cognitive function decline is more obvious than that of people who are not infected or have not been confirmed to be infected with the new coronavirus, which is equivalent to a decrease in IQ score of about 9 points (Note: The cognitive function decline shown in the survey results is based on memory, reasoning and executive function tasks, etc. Mainly several dimensions).
A study from Norway found that patients infected with the new coronavirus observed a decrease in Everyday Memory Questionnaire scores over a three-year period compared to a control group not infected with the new coronavirus.
Gu Xiaoying explained that these two studies used relatively objective evaluation tools, used measurable indicators to quantify the cognitive abilities of participants, and reached relatively objective conclusions, providing information on the decline in cognitive function caused by acute infection with the new coronavirus. supported by more reliable evidence.
But at the same time, the results of these two studies need to be interpreted with caution. "Both studies are observational studies, not randomized controlled clinical trials, and there are inevitable limitations caused by selection bias, information bias, etc." sex. In addition, the clinical significance of the cognitive decline scores derived from the study needs further evaluation."
“Although both studies concluded that COVID-19 infection will bring about a certain degree of cognitive decline, the British cohort study showed that subjects whose symptoms lasted for more than 12 weeks but recovered during follow-up had a lower degree of cognitive decline. Study subjects whose symptoms persisted for less than 12 weeks and had not recovered at follow-up were similar to study subjects whose symptoms recovered within 4 weeks or 4-12 weeks," Gu Xiaoying added.
Discussion on the "Long COVID-19" Mechanism
Zhang Hui told reporters from China Youth Daily and China Youth Daily that at present, the mechanism of "growing new coronavirus" is still at the level of hypothesis, which mainly includes the persistence of the virus, autoimmunity or immune response imbalance, microbial flora imbalance, and latent infection with the virus again. Activation, brain-gut axis and neuroendocrine system dysfunction, impaired coagulation function, unrepaired tissue damage, etc.
A study from the UK Biobank cohort (a cohort study is to divide a specific population into different subgroups according to whether they are exposed to a certain factor or the degree of exposure, and track the outcomes of two or more groups, such as disease What happens, an observational research method that compares the difference in the incidence of outcomes between groups to determine whether there is a causal association and the degree of association between these factors and the outcome - reporter's note) shows that compared with those who are not infected with the new coronavirus Compared with healthy controls, COVID-19 patients showed a greater decrease in brain volume before and after infection.
So, can it be inferred that the cause of cognitive decline caused by COVID-19 infection is related to damage to brain organs?
In the absence of scientific evidence, the answer is unknown.
"Since the scientific community lacks a unified definition of 'COVID-19' and has not yet reached a consensus on diagnostic criteria, it is very challenging to explore its mechanism at this time." Zhang Hui said.
Despite this, scientists at home and abroad have continued to study the new coronavirus and "long-COVID" and have made some progress.
"The new coronavirus has developed from the original strain to Omicron. The symptoms related to 'growing new coronavirus' are also different between different strains. For example, after the Omicron strain became popular, postural tachycardia syndrome (due to the virus Infection causes autonomic nervous dysfunction, so that when body position changes, abnormal autonomic nervous regulation function leads to symptoms of abnormally accelerated heart rate - reporter's note) related symptoms have received more widespread attention." Gu Xiaoying said.
Zhang Hui told reporters that in the past three years, Professor Cao Bin's team found in a cohort study of people who recovered from the original strain infection that the most common symptoms of "long COVID-19" include fatigue or muscle weakness, hair loss, sleep disorders, etc., and currently As the virus mutates, symptoms related to the cardiovascular system, such as palpitations (palpitation), chest pain, and postural tachycardia syndrome, have attracted more and more attention.
"Acute infections with other viruses, such as influenza, may also have chronic effects on the body. However, which virus will specifically have what impact on which specific group of people and in what time dimension still needs to be explored in a targeted manner." Gu Xiaoying said, "The new coronavirus provides an opportunity to more fully understand the chronic effects caused by acute viral infection."
Can “growing COVID-19” be prevented?
Some people may think that the original strain of the new coronavirus has gradually become less virulent as it continues to mutate and is now just a "large flu". Is it still necessary to prevent infection?
Gu Xiaoying believes that although the pathogenicity of the new coronavirus gradually decreases as it mutates, infection still needs to be prevented, because multiple infections will increase the risk of "growing new coronavirus."
To prevent "COVID-19", we need to reduce the number of infections from the source.
Personally, it is necessary to take good physical protection. During the epidemic period of a certain mutant strain, it is still necessary to wear a mask and maintain social distance to physically block the spread of the virus.
In addition, vaccines are also an important weapon in preventing infection with the new coronavirus and "growing new coronavirus".
"Vaccines can improve the body's resistance to viruses and reduce individual infection risks. Multiple studies have shown that vaccination before infection can reduce the risk of 'long COVID-19'." Zhang Hui said, "Because most of the vaccines currently used are for The original strain was developed, so there will inevitably be a certain degree of decline in protection against the changing mutant strains, so individuals still need to wear masks and pay attention to protection."
Don’t worry too much about “growing COVID-19”
Zhang Hui believes that there is no need to worry too much about "growing the new crown".
She explained that there is heterogeneity in the population with "COVID-19", and not everyone will get "COVID-19".
In fact, according to a 2022 national survey in the United States, approximately 6.9% of Americans had suffered from "long COVID-19" in 2022, and when symptoms persisted to the survey point, this number dropped to 3.4%.
Although the proportion is not high, when the 3.4% proportion is included in the large base of people who have recovered from the infection, the total number is still quite large.
Regarding these symptoms, Gu Xiaoying believes that there is no need to worry too much, but also to observe closely.
"We need to note that the vast majority of current studies on 'COVID-19' are cohort studies, and what is obtained is often the impact of COVID-19 infection at the population level, while there is a certain degree of heterogeneity at the individual level. .”
"When dealing with 'COVID-19', we must first have a correct understanding and know that it exists objectively; secondly, we must know how much impact it has on ourselves." Zhang Hui said, "If you only have some symptoms but do not affect your normal work and life, It does not affect organ function and is acceptable if it does not cause any trouble. But if it exceeds a person’s tolerance range, early diagnosis and treatment is necessary.”
The good news is that the scientific community has made preliminary progress in the treatment of "long COVID-19".
The results of a clinical trial of intestinal probiotics in the treatment of COVID-19 at the Chinese University of Hong Kong show that intestinal probiotics can reduce a series of symptoms of COVID-19, among which the most obvious benefit is in the symptom of inattention. .
Many clinical trials have also been carried out abroad, but relevant research is still ongoing.
"How to set up outpatient clinics for people with different symptoms of COVID-19 and use targeted drugs is the direction of our future efforts." Zhang Hui said.
"Opening a 'COVID-19' clinic is also a challenge because it requires support from experts with multidisciplinary backgrounds," Gu Xiaoying said.
As for the treatment of "COVID-19", it is necessary to obtain clear evidence support first. On the basis of the benefits of a single intervention, we can further explore and optimize the combination treatment plan so that people who are troubled by "COVID-19" can get better treatment.
China Youth Daily·China Youth Daily reporter Xia Jin Source: China Youth Daily