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Covid‐19 have shown small yet lasting effects on cognition and memory

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Covid‐19 may have an impact on people’s cognitive and memory abilities that lasts a year or more after infection.

A new study reveals small deficits in the performance of cognitive and memory tasks in people who had recovered from Covid‐19 compared with those who had not had Covid‐19. This includes people who had long-lasting symptoms (known as long Covid) that had eventually resolved.

The research also shows that the cognitive impact was larger for people who were hospitalised, who had ongoing long-lasting symptoms, or who were infected with earlier variants of the virus.

The study, called REACT long Covid, is led by the team of researchers behind the REACT programme, which began as one of the world’s largest and most comprehensive coronavirus monitoring studies in 2020 and is supported by the ݮƵ Imperial BRC and UK Research and Innovation.

Large Population study

The study, published in the New England Journal of Medicine, enrolled more than 140,000 participants, who undertook at least one cognitive task, with many having experienced Covid‐19 at various levels of severity and persistence.

Participants were asked to perform an innovative online cognitive assessment on the platform, which comprises tasks that can detect subtle changes in different aspects of their brain function, such as memory, reasoning, executive function, attention and impulsivity.

The study examined factors contributing to cognitive deficits in very fine detail while controlling for population variables such as age, demographics and pre-existing medical conditions.

Cognitive findings

The study revealed small cognitive deficits that were still detectable a year or more after infection, even in people who had short-spanned illness. They were larger for people who had symptoms lasting 12 weeks or more (consistent with long Covid), those who had been to hospital for their illness or those who were infected with one of the early variants of the virus.

People who had longer-lasting symptoms but whose symptoms had gone by the time they did the cognitive assessment showed small deficits that were similar to those of people who had a shorter-duration illness.

The results showed that Covid‐19 was associated with deficits in multiple areas of cognition, most notably in memory, such as the ability to remember pictures of objects that were viewed a few minutes earlier. The researchers believe this may be due to problems forming new memories rather than accelerated forgetting. People also showed small deficits in some tasks testing executive and reasoning abilities, such as those that require spatial planning or verbal reasoning.

The first author of the study Professor Adam Hampshire, from the Department of Brain Sciences at Imperial College London, said: “The potential long‐term effects of COVID‐19 on cognitive function have been a concern for the public, healthcare professionals, and policymakers, but until now it has been difficult to objectively measure them in a large population sample.

“By using our online platform to measure multiple aspects of cognition and memory at large scale, we were able to detect small but measurable deficits in cognitive task performance. We also found that people were likely affected in different ways depending on factors such as illness duration, virus variant and hospitalisation.”

Reduced impact

Professor Paul Elliott, senior author from the School of Public Health, director of the REACT programme and an honorary consultant in public health medicine at Imperial College Healthcare, said: “It is reassuring that people with persistent symptoms after Covid‐19 may expect to experience some improvement in their cognitive functions to similar levels as those who experienced short illness.

“Furthermore, the cognitive impact of Covid‐19 appears to have reduced since the early stages of the pandemic, with fewer people having persistent illness and cognition being less affected amongst those that were infected when Omicron was the dominant strain. However, given the large numbers of people who were infected, it will be important to continue to monitor the long-term clinical and cognitive consequences of the COVID‐19 pandemic.”

People
  • Professor Graham Cooke
    Professor Graham Cooke
    Theme lead and Professor of Infectious Diseases
  • Professor Helen Ward
    Professor Helen Ward
    Theme Lead, SGE, Professor of Public Health and Director, PERC
  • Professor Paul Elliott
    Professor Paul Elliott
    Theme Lead, Informatics & Biobanking
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