UK researchers have discovered that individuals with long-term COVID-19 symptoms, including brain fog, exhibited decreased performance in cognitive tasks even up to two years after contracting the virus.
A team from King’s College London conducted two rounds of online cognitive testing in 2021 and 2022 to evaluate the impact of COVID-19 infection on performance. The study collected data from over 3,000 participants of the COVID Symptom Study Biobank. These participants completed 12 tasks aimed at assessing memory, attention, reasoning, processing speed, and motor control.
The participants who experienced COVID-19 symptoms for 12 weeks or longer displayed the most significant decline in test scores. In these cases, the effect of COVID-19 on test accuracy was equivalent to that of a 10-year increase in age.
Notably, there was no notable improvement in test scores between the two rounds of testing, which were conducted nine months apart. By the second round, the average time since the participants’ initial COVID-19 infection was nearly two years.
Upon further analysis, the researchers divided the participants based on whether they felt fully recovered following their COVID-19 infection. Those who reported complete recovery performed similarly to individuals who had not contracted the virus at all. Conversely, participants who did not feel fully recovered after infection achieved lower average task accuracy scores.
Dr. Nathan Cheetham, a Senior Postdoctoral Data Scientist at King’s College London and the study’s lead author, stated:
“Our findings suggest that individuals experiencing long-term symptoms after recovering from COVID-19 still exhibit detectable effects on cognitive processes, such as word and shape recall, nearly two years after their initial infection.”
“However, it is encouraging that our tests indicate no impact on performance for those who felt fully recovered from COVID-19, even if they experienced symptoms for an extended period and could be categorized as having ‘long COVID.’ This study emphasizes the importance of monitoring individuals with the highest cognitive impairment due to COVID-19, tracking the development of their cognitive symptoms, and providing support for their recovery.”
Professor Claire Steves, a Professor of Ageing and Health at King’s College London, added:
“We utilized sensitive tests to measure speed and accuracy across various cognitive challenges. This study demonstrates that certain individuals exhibit measurable changes in these tests up to two years after contracting COVID-19. Two years after their initial infection, some individuals have not fully recovered, and their lives continue to be impacted by the long-term effects of the virus. We need further research to understand the underlying causes and explore potential interventions.”