Cognitive deficits related to COVID-19: The challenge of measuring association

Cognitive deficits related to COVID-19: The challenge of measuring association

2560 1707 Akshar Patel

There has been increasing worry about possible cognitive consequences related to COVID-19 and recent case studies have revealed neurological problems in severely affected patients.1 Growing evidence shows that certain individuals can have symptoms that persist beyond the initial illness.1 Often referred to as ‘Long COVID’, there are self-reports of ‘brain fog’, which include psychological symptoms such as low energy, problems concentrating, disorientation and difficulty finding the right words.1 There are also concerns regarding neurological consequences due to sepsis, hypoxia and immune hyperstimulation found in patients with COVID-19.1 Cognitive problems for those requiring a lengthy hospital stay or intubation are expected. It has not been established whether COVID-19 infection is associated with cognitive deficits at the population level.1 Measuring such association is challenging. Hampshire A et al. conducted a comprehensive cognitive test on patients that had recovered from COVID-19 to determine their level of cognitive deficit.

 

Cognitive deficit in patients with long COVID

Over 81,000 individuals completed the extended questionnaire and a total of 12,689 individuals suspected they had experienced COVID-19 with varying degrees of respiratory severity.1 From these individuals, 386 reported a positive biological test confirming COVID-19. Generalised linear modelling was applied to determine if global cognitive scores covaried with respiratory symptom severity. The analysis indicated there was a significant increase in the degree of cognitive deficit relative to the level of medical assistance received for COVID-19 respiratory symptoms.1 Patients that had been hospitalised with COVID-19 that were on a ventilator showed substantial cognitive deficits compared to those not on ventilators.1 The scale of the observed deficit was also not insubstantial. The global composite score reduction in cognitive functioning for patients hospitalised with ventilator use was greater than the mean deficit in 480 patients who indicated they had previously suffered a stroke, and 998 patients who reported having learning disabilities.1 After controlling for other confounding variables, the authors concluded that no observed deficits could be explained by differences in age, education, or other demographic or socioeconomic variables.1

 

Deficits in complex cognitive functioning

When examining the entire population, the most pronounced deficits were in complex cognitive functioning tests, such as reasoning, problem solving, spatial planning, and target detection.1 Analysis of individual task response time showed a significant delayed response time in tasks such as verbal analogies, Blocks, and Tower of London.1 More basic and simple functions such as working memory and emotional processing were largely unaffected. This aligns with earlier reports of ‘brain fog’ in patients with ‘Long-COVID’ that have trouble concentrating and have executive dysfunction at hospital discharge.1 The authors, however, caution in inferring a neurobiological or psychological basis for the observed deficits without specific brain imaging data and future concentrated research into the area.

 

A step towards understanding cognitive deficits in patients with long COVID

This analysis provided real evidence to support that COVID-19 infection is associated with cognitive deficits that persist into the recovery phase. Future comparisons with hospital recruited cohorts will provide further confirmation using the same cognitive tests. This study was not designed to determine the biological basis of the cognitive deficits in these patients. More work is needed to understand the underlying causes (e.g. fatigue, apathy and neurological changes) that can affect COVID-19 patients and will undoubtedly pose a challenge in the global post-pandemic recovery phase.

 


References

1. Hampshire A et al. EClinical Medicine. 2021;39:1–9.

Brainwork is supported by unrestricted grants from: