COVID-19 can impact memory and everyday cognitive tasks, but much of the existing evidence relies on extensive studies that depend on self-reporting and various influencing factors. A new study led by Imperial shows that cognitive effects of COVID-19 occur even in healthy individuals under controlled conditions, including infection with a comparable viral dose.
This research highlights specific changes in brain function scores among healthy young people, revealing significant differences in memory and cognition scores that persisted for up to a year after infection with SARS-CoV-2.
All scores remained within the expected normal ranges for healthy individuals, with none reporting lasting cognitive symptoms like brain fog. There was a small but measurable difference in cognitive performance among 18 infected young individuals compared to uninfected participants, all monitored under controlled conditions.
The research team recommends incorporating sensitive cognitive assessments in future studies to gain deeper insights into how infections impact brain function and to develop strategies to alleviate these effects when they occur.
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Senior author Professor Adam Hampshire, from the Department of Brain Sciences at Imperial College London and now based at King’s College London, explained, “We were only able to detect some of these effects because of the trial design, which used very sensitive tests and controlled conditions, with participant performance compared to their own pre-inoculation baselines. This enabled us to pick up on subtle changes of which the participants themselves appear not to have been aware.”
In this study, scientists analyzed data from a small group of healthy volunteers involved in the world’s first human challenge study for COVID-19 in 2021. The findings revealed subtle differences in test performance that lasted up to 12 months, although other factors could have affected later assessments.
During the trial, 36 healthy young participants with no prior immunity to the virus were infected with SARS-CoV-2 and monitored under controlled conditions until they were no longer infectious. Of these participants, 18 developed mild illness, while one remained asymptomatic.
Participants completed a range of tasks to evaluate various aspects of brain function—such as memory, planning, language, and problem-solving—using the Cognitron platform. Testing occurred before virus exposure, during their two-week stay in the clinical facility, and at multiple intervals over the following year.
Analysis showed that those infected with SARS-CoV-2 had statistically lower cognitive scores than uninfected volunteers during their infection and subsequent assessments. The most notable differences were found in memory and executive function tasks, including working memory, attention, and problem-solving. These score differences persisted for up to a year post-infection, with the uninfected group consistently performing slightly better overall.
“Future research could examine the biological links between respiratory infection and cognition in COVID-19, and even show how this impact compares with other conditions, such as Respiratory syncytial virus (RSV) or influenza.”
Co-author Professor Christopher Chiu, from the Department of Infectious Disease at Imperial College London, who led the COVID-19 human challenge study, said: “These latest findings from our study add more fine detail to the picture we have of COVID-19 and other respiratory infectious diseases.”
“Challenge studies can help us better understand how infections disrupt biological functions. Here, by showing biological effects that fall below what could be considered symptoms or disease, we were able to identify the smallest changes in these pathways. This could ultimately help us to develop new treatments to reduce or even block some of these effects, which we know in other settings can have lasting impacts on people’s lives.”
Journal Reference:
- William Trender, W., Hellyer, P., Killingley, B., et al. Changes in memory and cognition during the SARS-CoV-2 human challenge study. eClinical Medicine. DOI: 10.1016/j.eclinm.2024.102842