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People with mild cases of Covid-19 can still experience memory loss, poor attention span and fatigue up to nine months after infection, a study has found.
Research from Oxford University in the UK has revealed how widespread problems with mental processes can be, even for those who do not exhibit any other symptoms of long Covid.
In the study, participants who had tested positive for Covid-19 but did not report other traditional long Covid symptoms were asked to complete exercises to test their memory and cognitive ability.
The researchers found that participants were significantly worse at recalling personal experiences, known as episodic memory, up to six months after infection.
They also had a larger decline in their ability to sustain attention over time than uninfected individuals up to nine months after infection, Reuters reported.
"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," said Dr Sijia Zhao of the University of Oxford's Department of Experimental Psychology.
"Our findings reveal that people can experience some chronic cognitive consequences for months."
The researchers said episodic memory and attention span largely returned to normal after six and nine months, respectively.
Participants also performed well in tests of 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 randomised.
"However, despite this, differences between the Covid and non-Covid groups in terms of several specific measures of cognitive ability looked at in this study were striking," he said.
"Despite the limitations of non-randomised research, it seems unlikely that these results can be explained by systematic differences between the groups unrelated to Covid infection."
The effects of Covid-19 on the health and well-being of patients are still being explored.
Doctors in the UAE have reported an increase in the number of people suffering from insomnia and anxiety-related sleeping problems because of Covid-19.
Dr Hady Jerdak, a sleep specialist at Harley Street Medical Centre, said about 30 per cent of his patients come to him with “coronasomnia” – sleep problems related to stress caused by the pandemic.
Insomnia is experienced by many people who have long Covid, which is thought to affect as many as 100 million people worldwide.
“Sleep dysfunction is seen in Covid-19 sufferers, whether hospitalised or treated at home,” said Dr Pawan Kumar Srivastava, consultant in internal medicine at NMC Speciality Hospital, Al Nahda, Dubai.
“Studies conducted globally have shown 20 to 34 per cent of patients had sleep disorders which persisted even after recovery for months.
He said studies of long Covid patients suggest about 70 per cent of them suffer from sleep issues.