By Alistair Smout
LONDON (Reuters) - People with mild COVID-19 who do not suffer from other traditional "long COVID" symptoms may still show impaired attention and memory six to nine months after infection, a study from Britain's Oxford University has found.
Cognitive problems affecting concentration levels, along with forgetfulness and fatigue, are hallmarks of prolonged COVID - a condition that affects some after an initial bout of infection - but it has not been determined how widespread attention span problems may be after COVID-19 infection. .
In the study, participants who had previously tested positive for COVID-19 but did not report other traditional long-term COVID symptoms were asked to complete exercises to test their memory and cognitive abilities.
The researchers found that participants were significantly worse at remembering personal experiences, known as episodic memory, up to six months after infection.
They also had a greater decrease in their ability to maintain attention over time than uninfected individuals up to nine months after infection.
"What is surprising is that although our COVID-19 survivors did not feel more symptomatic at the time of testing, they showed impaired attention and memory," said Dr. Sijia Zhao from the Department of Experimental Psychology, University of Oxford.
"Our results reveal that people may experience some chronic cognitive consequences for several months."
The researchers said that over time, individuals showed episodic memory and attention span largely returned to normal after six and nine months, respectively.
Participants also performed well in testing other cognitive abilities, including working memory and planning, in the analysis of 136 participants.
Stephen Burgess of the MRC Biostatistics Unit at the University of Cambridge highlighted the small number of people involved in the study, adding that it was not randomized.
"Despite this, the differences between the COVID and non-COVID groups in terms of several specific measures of cognitive abilities looked at in this study were striking," he said.
"Despite the limitations of non-randomized research, it seems unlikely that these results can be explained by systematic differences between the groups not related to COVID infection."
(Report by Alistair Smout; Edited by Emelia Sithole-Matarise)