Covid-19 may have small but lasting effects on cognition and memory

Research led by Prof Paul Elliott (UK DRI at Imperial) has revealed 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 the virus. The study is published today in the New England Journal of Medicine.

Large population study

The study, called REACT Long Covid, 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 in the study were asked to perform an innovative online cognitive assessment 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 large scale of the study and the sensitivity of the computerised tests allowed factors that explained cognitive deficits post-Covid to be examined in very fine detail while controlling for population variables such as age, demographics and pre-existing medical conditions.

Cognitive findings

The study revealed:

• Those most likely to be affected were people who had symptoms for longer than 12 weeks, who were hospitalised for their illness, or infected with an early variant of Covid-19.
• Even in people who were only ill for a short time, small deficits were still detectable one year or more after infection.
• Covid-19 was associated with deficits in multiple areas of cognition, most notably memory, such as the ability to remember pictures of objects that were viewed a few minutes earlier. This may be due to problems forming new memories.

First author of the study Prof 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

Prof Paul Elliott added:

“It is reassuring that people with persistent symptoms after Covid-19, that had resolved, 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 during the time 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.”

Source: Imperial College London

To find out more about Prof Paul Elliott's research, visit his UK DRI profile. To keep up to date with the latest UK DRI news and events, sign up to receive our monthly newsletter.

Article published: 29 February 2024
Banner image: Shutterstock/Nhemz