Post-Covid cognitive loss is similar to 20 years of aging, study suggests

Several studies have already shown how Covid can be a disease with effects on the whole body, not just respiratory. Among the parts of the body that can be affected by the Sars-CoV-2 coronavirus is the nervous system, with well-known damage.

Post-Covid neurological effects, such as sleep difficulties, stress, anxiety, depression, memory loss and a feeling of “brain fog” (which encompasses difficulty concentrating, mental confusion and brain fatigue, among other symptoms) have already been described as possible sequels. of the disease.

Now, a new study suggests that the cognitive loss that can occur six to ten months after hospital discharge for Covid is similar to that of a natural aging 20 years.

The same cognitive impairment is equivalent to a loss of ten IQ points, according to research by scientists at the University of Cambridge and Imperial College London. The article describing the finding was published on the 28th in the eClinical Medicine journal, by the Lancet group.

In the study, the researchers also found that the severity of cognitive loss and neurological symptoms is linked to the most severe condition during the hospitalization period, with the need for mechanical ventilation and indication of inflammation in the body.

To calculate cognitive loss as a result of Covid, scientists performed neurological tests on 46 patients who were discharged from hospital after an infection with the virus. Patients were evaluated six to ten months after the acute infection.

The research also evaluated 460 individuals who had the same characteristics (gender, age, mother tongue and socioeconomic status) as the patients analyzed, but were not hospitalized with Covid, thus allowing to compare the results obtained from the tests in the control group and in the studied group.

The main differences observed were in the speed of response (delay to respond), greater forgetfulness of words or complete sentences and lesser spatio-temporal notion in the analyzed patients who had Covid sequelae compared to individuals who were not infected.

Still, comparing with what was observed in 28 patients diagnosed with dementia, the scientists saw that the cognitive damage in the most severe patients would be similar to that of patients suffering from degenerative disease, indicating a gradual loss of speed and cognitive ability post-Covid.

Recovery, according to the authors, is possible, but it is slow and gradual, with a very small sign of improvement observed in some of the individuals six months after discharge.

“While it is not yet statistically significant, this recovery at least points in one direction, that it is quite likely that some of these people will never fully recover,” said researcher David Menon, from the Division of Anesthesia at the University of Cambridge and the study’s last author. .

Possible causes

An important point of the study is that patients who had more cognitive sequelae after hospital discharge from Covid did not have a relevant diagnosis of any mental health condition before infection, such as a greater propensity for depression, anxiety or even post-traumatic stress, which could have worsened the post-Covid condition.

Among the hypotheses as to why patients discharged from the hospital after Covid-19 may develop cognitive sequelae are direct coronavirus infection in neurons, inefficient oxygenation or blood supply to the brain during the acute phase of the disease and the formation of small brain clots, according to the researchers. authors. However, more studies that relate these factors as possible causes of memory loss are needed.

The neurologist at the Instituto de Infectologia Emilio Ribas, Augusto Penalva, who commented on the study at the request of the report, considers that the inflammation mechanism after a severe Covid may be one of the factors that influence the effects of long Covid on the brain, but not the only one. .

“In our cohort [conjunto de pessoas analisadas], with more than 200 patients in São Paulo, we saw that more or less half have long-term Covid syndrome, but less than half of our patients had severe Covid. That is, even in mild cases the virus can cause neurological damage,” he said.

Penalva explains that the understanding of the different pathways that the coronavirus can affect in the brain has grown and that this will also imply a greater recovery process or not. “If what happened was an interruption of connections due to an inflammatory process, we know that this can be recovered, as the synapses go back and forth. Now, if there was cell loss, as with degenerative diseases, the process is more gradual”, said.