British scientists detect attention deficit and forgetfulness as a result of COVID-19

There are growing concerns about the possible cognitive consequences of COVID-19, following reports of long-term disease symptoms persisting in the chronic phase and case studies revealing neurological problems in severely ill patients. However, still information on the nature and wider prevalence of post-infection cognitive problems is lacking.

It has not yet been established whether COVID-19 infection is associated with cognitive deficits at the population level and how this differs with the severity of respiratory symptoms. Cognitive problems are expected in those who required an extended hospital stay or intubation.

Scientists are still investigating whether milder cases that weren’t hospitalized may also suffer from objectively measurable cognitive deficits.

Cognitive data on pre- and post-COVID-19 illnesses is scarce because infection is unpredictable. This problem is compounded by the cost of performing standard face-to-face cognitive assessments on populations large enough to capture such change, or to account for potentially confusing population variables that correlate with performance. cognitive. This motivated a work team led by Adam Hampshire.

The Department of Brain Sciences, Center for Research and Care Technology of the Dementia Research Institute at Imperial College London took a large-scale approach, whereby people who have recovered from COVID-19 infection they were compared to controls obtained at the same time, taking into account the uneven socio-demographic distribution of virus prevalence and any associated demographic variability in cognition.

In his recent publication in The Lancet Specialists analyzed data from 81,337 people who completed the extended questionnaire to test the hypothesis that those who had recovered from COVID-19 would have objective cognitive deficits during attention, working memory, and other tests. problem solving and emotional processing. They also determined whether the extent and / or nature of the cognitive deficit detected was related to the severity of the respiratory symptoms depending on the level of medical management, positive verification of the infection by a biological test, or the elapsed time. since the onset of the disease. .

The document found that people who had recovered from COVID-19, including those who were no longer reporting symptoms, had significant cognitive deficits. compared to controls for age, gender, education level, income, racial / ethnic group, pre-existing medical conditions, fatigue, depression and anxiety.

“The deficits had a substantial effect size for people who had been hospitalized,” explains the lead author of the article, “but also for out-of-hospital cases who had laboratory confirmation of COVID infection- 19 “. Analysis of premorbid intelligence markers did not confirm that these differences were present before infection.. More detailed analysis of performance on the subtests supported the hypothesis that COVID-19 has a multidomain impact on human cognition.

“It has long been known that Covid-19 also attacks neurons and invades the brain, so there is undoubtedly a damaging effect as a result of infection,” said German Cueto, neurologist and academic at the medical school. from the University of Valparaíso. .

“Our analyzes,” says William Tender, second author of the research, “provide converging evidence to support the hypothesis that COVID-19 infection is associated with cognitive deficits that persist in the recovery phase.”

Scientists’ deficits varied in magnitude with the severity of respiratory symptoms, linked to the positive biological verification of having had the virus even among the mildest cases, and which could not be explained by differences in age, education or other demographic and socio-economic variables. These conditions remained in those who had no other residual symptoms and were more extensive than common pre-existing conditions associated with susceptibility to the virus and cognitive problems.

In terms of cognitive profile, the applied assessment battery included tests designed to allow large-scale examination of the variability of different aspects of cognition within the general population. The deficits affected several tests but to different degrees. When examining the whole population, the deficits were more pronounced for paradigms that took advantage of cognitive functions such as reasoning, problem solving, spatial planning, and target detection, while they were were lighter in tests of simpler functions such as working memory and emotional processing.

This results consistent with reports of prolonged COVID, where brain fog, difficulty concentrating and finding the right words are common.

“Speculatively,” Hampshire adds, “we think there are probably several contributing factors. For example, previous studies in hospitalized patients with respiratory disease not only demonstrate objective and subjective cognitive deficits, but also suggest that these persist for some after 5 years of follow-up. ”Consequently, the observation of post-infection deficits in the ventilator subgroup was not entirely surprising. On the contrary, the magnitude of the deficits in cases unrelated to mechanical ventilation, especially those who stayed at home, was unexpected given the limited literature on other respiratory illnesses such as the common cold.

While these deficits were on average small in scale for those who stayed at home, they were larger for people who had received a positive confirmation of COVID-19 infection. “A corollary of this is that the cognitive deficits associated with other respiratory illnesses that are mistakenly self-diagnosed as COVID-19 are likely to be insignificant,” adds Hampshire. The observed correlation with the severity of respiratory symptoms strongly agrees with this view.; however, there have been case reports of other forms of neurological damage in COVID-19 survivors, including some where such damage was the first symptom detected. “

Therefore, in the present study, bio-positive cases who reported illness but stayed at home showed significant cognitive impairment. Based on this, the researchers propose that a timely challenge is to link the multidimensional profile of the observed cognitive deficits with the image markers that can confirm and differentiate the underlying psychological and neuropathological sequelae of COVID-19 deficiency due to COVID. -19. “A more complete understanding of the glaring deficits shown by our study will allow better preparation for the challenges of post-pandemic recovery,” concludes Tender.

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