- A recent study suggests a link between severe COVID-19 requiring hospitalization and deficits in cognitive function that persist 6 to 10 months after illness onset.
- Cognitive deficits in COVID-19 survivors were similar in magnitude to the decline in cognitive function that normally occurs in people between the ages of 50 and 70.
- The gradual recovery, if any at all, of these persistent cognitive deficits highlights the importance of understanding the underlying mechanisms and developing treatment strategies.
- Mild cases of COVID-19 may report persistent cognitive symptoms, but the study authors report that the incidence is higher in severe cases, with
33 % -76%presenting with cognitive symptoms 3 to 6 months after hospitalization.
A recent study published in the journalOnline clinical medicinesuggests that severe COVID-19 may be associated with persistent cognitive deficits, equivalent to a 10-point drop in IQ. In this study, severe COVID-19 was defined as COVID-19 requiring hospitalization and intensive care.
These cognitive deficits persisted until at least 6 months after acquiring SARS-CoV-2 infection, with progressive improvement, if any, of these cognitive symptoms. These findings underscore the importance of longer-term support for patients who have recovered from severe COVID-19.
According to official data from 2020, which is the same year this study drew its data from, about 4 in 10 adults over the age of 18 are at risk of developing severe COVID-19 in the United States.
A significant minority of individuals infected with SARS-CoV-2 exhibit persistent cognitive impairment.
Although persistent cognitive symptoms are also seen in people with mild COVID-19, such deficits in cognitive function are more common in people with severe COVID-19. Previous studies suggest that
However, further research is needed to understand the specific aspects of cognitive function that are affected after severe COVID-19 and the factors that predict these cognitive symptoms.
Previous studies characterizing persistent cognitive symptoms in patients with COVID-19 have relied on self-reports, which are likely to be biased. Other studies have used pen-and-paper neuropsychological tests to assess cognitive function.
However, these tests lack the sensitivity needed to detect small changes in cognitive function or to distinguish between the various domains or aspects of cognitive function affected by SARS-CoV-2 infection.
To address these concerns, the authors of the current study used computerized cognitive testing to objectively characterize specific areas of cognitive function affected after severe acute COVID-19. These computerized tests also allowed the researchers to assess the extent of these cognitive deficits.
People with COVID-19 also have persistent mental health symptoms such as anxiety, depression, fatigue and post-traumatic stress disorder (PTSD), which could contribute to deficits in cognitive function.
Another objective of the current study was to determine whether these mental health symptoms mediate persistent cognitive deficits in COVID-19 patients.
The current study involved 46 patients who were previously hospitalized with severe COVID-19 and received intensive care at Addenbrooke’s Hospital in Cambridge, England. Former COVID-19 patients completed a series of computerized cognitive tests during a return visit to the hospital, on average 6 months after illness onset.
The performance of the 46 participants in the cognitive tests was compared with that of 460 individuals in the control group. Individuals in the control group were not hospitalized with COVID-19 and were matched for age, gender, and education level. The researchers also used self-reports to assess symptoms of anxiety, depression, and PTSD.
Researchers found that COVID-19 patients had a lower score and slower response time in cognitive tests than matched controls. People with COVID-19 showed more pronounced deficits in specific areas of cognition, including processing speed, attention, memory, reasoning and planning.
Notably, cognitive function deficits in COVID-19 survivors were not associated with mental health symptoms present at the time of cognitive testing, such as depression, anxiety, and PTSD.
Instead, performance on cognitive tests was correlated with the severity of acute illness. For example, cognitive deficits were more pronounced in people requiring mechanical ventilation.
The researchers then compared the performance of COVID-19 survivors with more than 66,000 people from the general population.
The magnitude of cognitive impairment in COVID-19 survivors was equivalent to the expected age-related cognitive decline over the 20-year period between ages 50 and 70.
The study’s lead author, Professor David Menon, Head of Anesthesia Division at the University of Cambridge, says: “Cognitive impairment is common to a wide range of neurological disorders, including dementia, and even routine aging, but the patterns we observed — the cognitive “fingerprints” of COVID-19 — were distinct from all of that.
Dr Betty Raman, a cardiologist at the University of Oxford, said Medical News Today“This prospective cohort study of 46 people recovering from severe COVID-19 and a large normative reference population by Hampshire and colleagues showed a clear association between severity of infection and degree of cognitive impairment. .”
“This multidimensional characterization of cognition provides a nuanced understanding of distinct patterns of cognitive impairment during the recovery phase of severe COVID-19. Future efforts are needed to understand how this pattern varies in the context of other post-infectious syndromes and serious diseases.
The study found that these cognitive deficits persisted for up to 6 to 10 months after the onset of COVID-19, and there was only gradual improvement, if any, in cognitive performance. The persistence of these cognitive deficits highlights the importance of understanding the mechanisms underlying these symptoms.
Scientists have proposed multiple mechanisms, such as direct infection of the brain with SARS-CoV-2 and disruption of blood supply to the brain, to explain persistent cognitive symptoms in COVID-19 patients. Among these mechanisms, systemic or global
Dr. Roger McIntyre, professor of psychiatry and pharmacology at the University of Toronto, said DTM“Inflammatory activation appears to mediate these findings, underscoring the dangers of prolonged immune activation. The next steps are to more fully unravel the biological mechanisms and identify prevention and treatment strategies.
Discussing the main questions that need to be addressed, Dr Paul Harrison, Professor of Psychiatry at the University of Oxford, said:
“This study shows that these deficits can be significant and persist for more than 6 months after the acute illness. The results are compelling and important and raise further questions. For example, what happens after a less severe infection? How long do deficits last? What causes them and, above all, how can they be treated or prevented? »