People who have had COVID-19 but do not complain of Long COVID symptoms in everyday life can still show decreased attention and memory for up to nine months, new research has revealed.
Previous studies have shown that after acute COVID-19 infection, some people can continue to suffer from cognitive symptoms such as difficulties in concentrating – known as ‘brain fog’ – as well as forgetfulness and fatigue.
These symptoms have become staple features of post-COVID syndrome, or Long COVID.
But it was not known whether cognitive performance can also be affected in individuals who had mild symptoms and report no concerns after recovery from acute COVID infection.
Now, through a study from Oxford’s Department of Experimental Psychology and Nuffield Department of Clinical Neurosciences, it has been revealed that people can experience degraded attention and memory for up to six to nine months.
“Our findings reveal that people can experience some chronic cognitive consequences for months,” said Dr Sijia Zhao, of the University of Oxford.
In the study, participants were asked to complete a number of exercises to test their memory and cognitive ability, with a focus on cognitive functions critical for daily life, such as sustaining attention, memory, planning and semantic reasoning.
All the participants had previously had COVID-19 but were not significantly different from a control group at the time of testing on factors such as fatigue, forgetfulness, sleep patterns or anxiety.
The researchers found that the participants performed well in most abilities tested, including working memory and planning, but they displayed significantly worse episodic memory – up to six months post-COVID infection – and a greater decline in the ability to sustain attention over time – for up to nine months – than uninfected individuals.
Dr Zhao said: “What is surprising is that although our Covid-19 survivors did not feel any more symptomatic at the time of testing, they showed degraded attention and memory.”
Professor Masud Husain added: “We still do not understand the mechanisms that cause these cognitive deficits, but it is very encouraging to see that these attention and memory return largely to normal in most people we tested by six to nine months after infection, who demonstrated good recovery over time.”
