The effects of COVID-19 on cognitive performance in a community-based cohort: a symptom study biobank prospective cohort study 2023 Cheetham et al

Full title:
The effects of COVID-19 on cognitive performance in a community-based cohort: a COVID symptom study biobank prospective cohort study

Summary

Background
Cognitive impairment has been reported after many types of infection, including SARS-CoV-2. Whether deficits following SARS-CoV-2 improve over time is unclear. Studies to date have focused on hospitalised individuals with up to a year follow-up. The presence, magnitude, persistence and correlations of effects in community-based cases remain relatively unexplored.

Methods
Cognitive performance (working memory, attention, reasoning, motor control) was assessed in a prospective cohort study of participants from the United Kingdom COVID Symptom Study Biobank between July 12, 2021 and August 27, 2021 (Round 1), and between April 28, 2022 and June 21, 2022 (Round 2). Participants, recruited from the COVID Symptom Study smartphone app, comprised individuals with and without SARS-CoV-2 infection and varying symptom duration. Effects of COVID-19 exposures on cognitive accuracy and reaction time scores were estimated using multivariable ordinary least squares linear regression models weighted for inverse probability of participation, adjusting for potential confounders and mediators. The role of ongoing symptoms after COVID-19 infection was examined stratifying for self-perceived recovery. Longitudinal analysis assessed change in
cognitive performance between rounds.

Findings
3335 individuals completed Round 1, of whom 1768 also completed Round 2.

At Round 1, individuals with previous positive SARS-CoV-2 tests had lower cognitive accuracy (N = 1737, β = −0.14 standard deviations, SDs, 95% confidence intervals, CI: −0.21, −0.07) than negative controls.

Deficits were largest for positive individuals with ≥12 weeks of symptoms (N = 495, β = −0.22 SDs, 95% CI: −0.35, −0.09).

Effects were comparable to hospital presentation during illness (N = 281, β = −0.31 SDs, 95% CI: −0.44, −0.18), and 10 years age difference (60–70 years vs. 50–60 years, β = −0.21 SDs, 95% CI: −0.30, −0.13) in the whole study population.

Stratification by self-reported recovery revealed that deficits were only detectable in SARS-CoV-2 positive individuals who did not feel recovered from COVID-19, whereas individuals who reported full recovery showed no deficits.

Longitudinal analysis showed no evidence of cognitive change over time, suggesting that cognitive deficits for affected individuals persisted at almost 2 years since initial infection.

Interpretation
Cognitive deficits following SARS-CoV-2 infection were detectable nearly two years post infection, and largest for individuals with longer symptom durations, ongoing symptoms, and/or more severe infection. However, no such deficits were detected in individuals who reported full recovery from COVID-19. Further work is needed to monitor and develop understanding of recovery mechanisms for those with ongoing symptoms.

Funding
Chronic Disease Research Foundation, Wellcome Trust, National Institute for Health and Care Research, Medical Research Council, British Heart Foundation, Alzheimer's Society, European Union, COVID-19 Driver Relief Fund, French National Research Agency.

https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(23)00263-8/fulltext

 

Evening Standard article discussing the study.

Long Covid brain fog similar to ageing a decade, researchers say
People who had symptoms of the virus for 12 weeks or more were most affected, a study found.

Brain fog associated with long Covid is comparable to ageing 10 years, researchers have suggested.
A study by King’s College London explored the impact of long Covid on thinking and memory skills for a paper published in eClinicalMedicine.

The team studied people included in the Covid Symptom Study Biobank who were recruited via the Covid Symptom Study smartphone app. Those in the study included people with Covid and varying degrees of symptoms and people without the illness.

They were given 12 tasks testing memory, attention, reasoning, processing speed and motor control.

Researchers said the impact of Covid on test accuracy “was comparable in size to the effect of a 10-year increase in age” and scores were most affected in people who had symptoms of the virus for 12 weeks or more.

The study was split into two rounds nine months apart.
Some 3,335 people completed the first round, which took place in July and August 2021, with 1,768 going on to complete the second round between April and June 2022.

Researchers found no significant improvement in scores between two rounds.
By the time the second round was conducted, the average time since participants’ initial infection was almost two years.

https://www.standard.co.uk/news/health/people-b1095986.html

 

KCL
Some people's brain function still affected by Long COVID years after infection

Some people's brain function still affected by Long COVID years after infection - King's College London (kcl.ac.uk)

 

The Mirror and the Independent have also reported on it.

https://www.independent.co.uk/news/health/long-covid-brain-fog-research-b2379570.html
https://www.mirror.co.uk/news/health/brits-long-covid-symptoms-age-30521234

This study is certainly gaining some media attention online. I hope it'll be the same in print.

 

That would indeed be the very definition of recovery.

But this is really, really bad, and also known to us for many years, reported by millions, to widespread clinical indifference:

Although kind of not helpful on the 10 year thing. There is no significant cognitive decline between 20 and 30 years-old, something that holds up all the way to the 60's, probably. So this really would be only as a comparison to old age, otherwise it just doesn't make sense. And the decline from 70-80 is obviously more significant than 60-70. It really understates the issue, frankly.

 

Though to be fair they are confirming that people who report full recovery (i.e. no overt symptoms) do indeed have no detectable cognitive deficits with sensitive testing.

 

Yeah on second thought this is still very much relevant, permanent damage would be a much more serious issue, but the language they used obfuscates a bit what patients mean by recovered, which is a common issue in chronic illness.