POST COVID: Study Reports Concerning Findings Of Cognitive Deficits Among Many Recovered COVID-19 Patients!
: A new study by researchers from Imperial College London-UK, University of Southampton-UK, University of Cambridge-UK and King’s College London-UK and University of Chicago-USA has reported concerning findings showing that patients who had recovered from COVID-19 exhibited significant cognitive deficits.
Numerous past studies have revealed neurological problems in severely affected COVID-19 patients. There is however little information regarding the nature and broader prevalence of cognitive problems post-infection or across the full spread of severity. The study team analyzed cognitive test data from 84,285 Great British Intelligence Test participants who completed a questionnaire regarding suspected and biologically confirmed COVID-19 infection. Individuals who had recovered, including those no longer reporting symptoms, exhibited significant cognitive deficits when controlling for age, gender, education level, income, racial-ethnic group and pre-existing medical disorders. They were of substantial effect size for individuals who had been hospitalized, but also for mild but biologically confirmed cases who reported no breathing difficulty. Finer grained analyses of performance support the hypothesis that COVID-19 has a multi-system impact on human cognition.
The study findings were published on a preprint server but are currently being peer-reviewed. https://www.medrxiv.org/content/10.1101/2020.10.20.20215863v1
The new research was based on cognitive test data available from more than 84,000 participants, not only identified the deficits among people who had severe disease but also among individuals with mild disease who had not even reported breathing difficulties.
The detailed application of generalized linear modeling (GLM) showed that the observed deficits could not be explained by differences in age, education, underlying medical conditions, or other demographic and socioeconomic variables.
Corresponding author, Dr Adam Hampshire from the Computational, Cognitive & Clinical Neuroimaging Laboratory, Division of Brain Sciences, Imperial College London told Thailand Medical News, “Our analyses provide converging evidence to support the hypothesis that COVID-19 infection likely has consequences for cognitive function that persist into the recovery phase. These results should act as a clarion call for more detailed research investigating the basis of cognitive deficits in people who have survived SARS-COV-2 infection.”
To date, a mounting body of evidence suggests that individuals who develop severe COVID-19 can develop neurological problems such as those arising from stroke, microbleeds, and inflammatory syndrome.
Certain other studies have also reported elevated levels of autoantibodies in the cerebrospinal fluid of patients, changes in the white brain matter, and psychological consequences at the point of hospital discharge.
But to date, there is little information regarding whether COVID-19 is associated with cognitive impairment at the population level post-infection or across differing degrees of severity.
Dr Hampshire further added, "Measuring such associations is challenging. Longitudinal collection of cogn
itive data from pre- to post-COVID is extremely problematic because the infection is unpredictable. Furthermore, it is important to include key minority sub-populations, for example, older adults, racial-ethnic groups, and people with pre-existing medical conditions."
The study team conducted a large-scale, cross-sectional analysis of recovered COVID-19 patients and healthy controls adjusted for potential confounders including age, education, underlying medical conditions, or other demographic and socioeconomic variables.
The study team analyzed cognitive test data available for 84,285 individuals who participated in the “Great British Intelligence Test” and who also completed a questionnaire about suspected and biologically confirmed COVID- 19.
Dr Hampshire said, “Due to the high visibility of the study, this cohort spanned a broad age and demographic range.”
The primary aim was to determine whether recovered COVID-19 patients showed any signs of cognitive deficits related to semantic problem solving, spatial working memory, selective attention, and emotional processing.
The study team also aimed to establish whether the extent or type of deficit was associated with the severity of respiratory symptoms, which was gauged by the degree of medical assistance required.
Alarmingly, participants who had recovered from COVID-19 exhibited significant cognitive deficits, even after GLM had controlled for age, gender, education level, income, occupational status, racial-ethnic group, country of residence, first language, and pre-existing medical conditions.
Dr Hampshire added, “Individuals who recovered from suspected or confirmed COVID-19 perform worse on cognitive tests in multiple domains than would be expected given their detailed age and demographic profiles.”
Interestingly the effect size was not only substantial among those who had required hospitalization but also among those who had not needed hospital treatment and had not even reported breathing difficulties.
Also hospitalized cases showed large-to-medium scale global performance deficits, depending on whether they had required a ventilator or not.
When compared with controls, the mean reduction in global composite score among the subgroup requiring a ventilator (-0.57 standard deviations [SDs]) was larger than the mean deficit among 512 individuals who reported previous stroke (-0.40 SDs) and the mean deficit among 1,016 who reported learning disabilities (-0.49 SDs).
Dr Hampshire said “For comparison, in a classic intelligence test, 0.57 SDs equates to an 8.5-point difference in IQ.”
Also those who had not required support in hospital and remained at home exhibited small but statistically significant global performance deficits that scaled with the severity of respiratory symptoms.
It was found that the deficits ranged from -0.12 SDs among 176 individuals supported at home for respiratory difficulty; to -0.10 SDs among 3,466 who had respiratory symptoms but no medical assistance; to -0.04 SDs among 9,201 who were ill but did not have respiratory problems.
Importantly finer grained analysis of the deficits showed that they were broad, affecting multiple cognitive domains
They were however more pronounced for semantic problem solving and visual selective attention than for more straightforward functions such as working memory span and emotional processing.
Dr Hampshire added, “Individuals who have recovered from COVID-19 infection show particularly pronounced problems in multiple aspects of higher cognitive or ‘executive’ function.”
The study team says this finding is in accord with preliminary reports of executive dysfunction among some patients at the point of hospital discharge, as well as previous studies of ventilated patients with acute respiratory distress syndrome prior to the pandemic.
The study team concluded, “A fuller understanding of the deficits is needed. Our analyses of detailed cognitive assessment and questionnaire data from tens of thousands of datasets, collected in collaboration with BBC2 Horizon, align with the view that there are chronic cognitive consequences of having COVID-19.”
The added, “Further work is required to interrelate the deficits to underlying neurological changes, and to disambiguate the associated pathological processes and cross compare to other respiratory viruses. A fuller understanding of the marked deficits that our study shows will enable better preparedness in the post-COVID-19 pandemic recovery challenges.”
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