Long Covid can have an ‘objectively measurable’ impact on brain function and ability for a year or even longer, research has suggested.
A study published in the New England Journal of Medicine has concluded that this “brain fog” – a well-recognised symptom of long Covid – can be seen in people with lingering, unresolved symptoms of Covid-19.
Where symptoms had not resolved themselves within 12 weeks, people reported “deficits” in performance on tasks involving memory, reasoning and decision making. These deficits had a quantifiable impact, the researchers from Imperial College London concluded.
The study assessed more than 140,000 people in summer of 2022. Participants were given online cognitive tests designed to test their memory, attention span, reasoning and other aspects of brain function.
About 3.5% of the cohort had experienced Covid-19 symptoms that persisted beyond 12 weeks, normally the measure of long Covid. Of these, about two-thirds still had symptoms at the time of the assessment.
Long Covid
Leaky blood vessels could be key to long Covid ‘brain fog’
Line manager support key to long Covid return to work
Long Covid: Being vaccinated ‘consistently’ reduces risk, study finds
The analysis found small deficits were still detectable a year or more after infection, for those who had been infected and no longer had symptoms.
The difference in test scores between those who had been infected and those who had not was equivalent to about three IQ points, had they been given an IQ test.
For an individual, this size of change is unlikely to be noticeable, the researchers argued, although, for some people, they may experience more pronounced effects.
Those patients with unresolved symptoms that had persisted for more than 12 weeks were found to have a larger deficit, equivalent to six IQ points.
As the research team concluded: “We found objectively measurable cognitive deficits that may persist for a year or more after Covid-19. We also found that participants with resolved persistent symptoms had small deficits in cognitive scores, as compared with the no-Covid-19 group, that were similar to those in participants with shorter-duration illness.
“Early periods of the pandemic, longer illness duration, and hospitalisation had the strongest associations with global cognitive deficits. The implications of longer-term persistence of cognitive deficits and their clinical relevance remain unclear and warrant ongoing surveillance.”
Last year, the Office for National Statistics estimated about two million people in the UK were experiencing self-reported long Covid.
Previous Imperial College analysis has found tens of thousands of people in England may have symptoms that had lasted a year or more after infection.
Sign up to our weekly round-up of HR news and guidance
Receive the Personnel Today Direct e-newsletter every Wednesday
