Summary: Good adults who contracted COVID-19 experienced sporadically but tangible memory and mental declines that lasted up to a year. These variations were discovered through delicate tests conducted under controlled circumstances, but all ratings remained within normal ranges and none of the individuals reported lasting mental symptoms.
The study demonstrates the potential need for solutions to attenuate brain function and demonstrates how also mild COVID-19 can have an impact on brain function. More studies are needed to discover how COVID-19 compares with various respiratory infections, like virus, in terms of cognitive effects.
Important Information:
- COVID-19 can produce simple cognitive changes in storage and problem-solving for up to a month.
- These results were detected through delicate cognitive tests, never self-reports.
- Participants in the study did not experience any long-term, discernible mental ailments.
Origin: Imperial College London
A new study from Imperial’s individual problem study of COVID-19 has revealed sizable differences in the storage and thinking scores of healthy volunteers who were infected with SARS-CoV-2, which lasted up to a month after infection.
No single reported experiencing any long-term mental symptoms like brain fog, according to the researchers, and all scores fell within expected regular ranges for healthy people.
The results,  , published , in the journal , eClinicalMedicine, show a little but tangible difference following very intense mental screening of 18 healthy young persons with disease compared to those who did not become infected, monitored under controlled medical problems.
The team claims that incorporating such introspective research into upcoming studies could provide more in-depth insights into how infections may affect brain function and could help identify ways to stop these processes when they lead to symptoms.
We know that COVID-19 can have lasting effects on our memory and ability to perform common cognitive tasks, according to senior author Professor Adam Hampshire from the Department of Brain Sciences at Imperial College London and currently based at King’s College London.
However, much of the , scientific evidence , we have comes from large studies based on self-testing and reporting, or where there’s a range of variables that could increase or reduce these effects.
Our research further demonstrates how respiratory infections can have an impact on specific aspects of brain function and how these cognitive effects can be replicated in healthy people even under carefully controlled circumstances, including when they are infected with a comparable dose of virus.
Because the trial design used very sensitive tests and controlled conditions, with participants who performed compared to their own baselines before the immunization, we were only able to detect some of these effects. This made it possible for us to notice subtle changes that the participants allegedly did not know about.
COVID-19 and cognition
Previous studies that included patients with a wide range of severities demonstrated that COVID-19 can have a long-term impact on people’s brain function. One such study, led by Imperial and involving more than 140, 000 people, found that COVID-19 survivors had a few minute or more of differences in their cognitive and memory skills, with those differences still present a year or more after infection.
Researchers who participated in the first human challenge study to date for COVID-19 in 2021 analyzed findings from a small group of healthy volunteers in the most recent study. The results reveal subtle variations in how they performed on the same tests, which lasted for up to 12 months, despite the possibility that additional and later factors may have had an impact on later testing.
During the trial, 36 healthy, young participants with no previous immunity to the virus were infected with SARS-CoV-2 and monitored under controlled clinical conditions. They were kept under strict surveillance and were kept there until they stopped spreading. From the group, 18 participants became infected and developed mild illness, one without symptoms.
Participants also performed sets of tasks to measure multiple distinct aspects of their , brain function, including memory, planning, language and problem solving, using the Cognitron platform. Participants took the tests before getting the virus, during the two weeks they spent in the clinic, and then repeatedly for up to a year.
In addition to their baseline cognitive scores, analysis revealed that those who contracted SARS-CoV-2 had statistically lower cognitive scores both during and after the infection. The main differences in scores were found in executive function tasks, including working memory, attention, and problem-solving.
Up until a year after infection, there were no significant differences in scores between groups, with the uninfected group showing overall performance differences.
The researchers point out that none of the volunteers reported persistent cognitive symptoms despite the small differences that were observed. They also highlight the study’s drawbacks, such as the small sample size and the fact that the majority of the participants were white men, and require extra caution when extrapolating the findings to the general population.
They explain that 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, who led the COVID-19 human challenge study and is a professor in the Department of Infectious Disease at Imperial College London, 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 provide a tool for better understanding how infections disrupt a range of biological functions. We were able to identify the smallest changes in these pathways by demonstrating biological effects that fall below what might be regarded as symptoms or diseases.
” We now have the knowledge that some of these effects, which we know in other settings can have long-lasting effects on people’s lives, can be reduced or even blocked,” says Dr. Baez.
About this Long-COVID and memory research news
Author: Ryan O’Hare
Source: Imperial College London
Contact: Ryan O’Hare – Imperial College London
Image: The image is credited to Neuroscience News
Original Research: Open access.
” Changes in memory and cognition during the SARS-CoV-2 human challenge study” by William Trender et al. EClinicalMedicine
Abstract
Changes in memory and cognition during the SARS-CoV-2 human challenge study
Background
Patient-reported outcomes and cross-sectional evidence show an association between COVID-19 and persistent cognitive problems. The causal basis, longevity and domain specificity of this association is unclear due to population variability in baseline cognitive abilities, vulnerabilities, virus variants, vaccination status and treatment.
Methods
Thirty-four young, healthy, seronegative volunteers were inoculated with Wildtype SARS-CoV-2 under prospectively controlled conditions. Volunteers completed daily physiological measurements and computerised cognitive tasks during quarantine and follow-up at 30, 90, 180, 270, and 360 days. Linear modeling assessed the differences between “infected” and “inoculated but uninfected” people.
The baseline corrected global cognitive composite score across the battery of tasks given to the volunteers was the main cognitive endpoint. Baseline corrected scores from individual tasks were among the exploratory cognitive endpoints.
The study was registered on , ClinicalTrials. gov , with the identifier , NCT04865237 , and took place between March 2021 and July , 2022.
Findings
One of the 18 volunteers had no symptoms, and the other had a mild illness, according to qPCR’s assessment of sustained viral load. Infected volunteers showed statistically lower baseline-corrected global composite cognitive scores than uninfected volunteers, both acutely and during follow up ( mean difference over all time points , = , −0.8631, 95 % CI , = , −1.3613,  , −0.3766 ) with significant main effect of group in repeated measures ANOVA ( F ( 1, 34 )  , = , 7.58, p , = , 0.009 ).
Sensitivity analysis replicated this cross-group difference after controlling for community upper respiratory tract infection, task-learning, remdesivir treatment, baseline reference and model structure. Memory and executive function tasks showed the largest between-group differences. No volunteers shared persistent subjective cognitive symptoms.
Interpretation
These results support larger cross-sectional studies that show that mild Wildtype SARS-CoV-2 infection can be followed by brief, gradual changes in memory and cognition that last at least a year. These minor changes have a mechanistic basis, but their clinical applications are still a mystery.
Funding
This study was funded through the UK Vaccine Taskforce of the Department for Business, Energy and Industrial Strategy ( BEIS ) of Her Majesty’s Government.  ,
