Long Covid infections can cause some people to develop face recognition difficulties and navigation problems, according to a new study.
Previous studies have shown that infection with the coronavirus can cause a range of neurological symptoms, such as loss of smell and taste, and impairments in attention and memory, known as “brain fog”.
The new study, published in the journal cortexsuggests some individuals may develop ‘prosopagnosia’, also known as face blindness, after symptoms consistent with Covid.
Researchers, including those from Dartmouth College in the US, evaluated a 28-year-old customer service representative and part-time portrait artist, identified only as Annie, who was diagnosed with Covid in March 2020.
Annie reported difficulties with face recognition and navigation soon after her symptoms returned two months later.
“When I first met Annie, she told me that she couldn’t recognize the faces of her family,” study lead author Marie-Luise Kieseler said in a statement.
After meeting her parents for the first time after contracting Covid, Annie reported that she couldn’t recognize them.
When she walked past her parents again, her father called her, she said.
“It was like my father’s voice coming out of a stranger’s face,” the 28-year-old said, adding that she now relies on voices to identify people she knows.
Annie also developed “navigation deficits” after she had Covid.
“The combination of prosopagnosia and navigational deficits that Annie had caught our attention because the two deficits often go hand in hand after someone has either brain damage or developmental deficits,” said the study’s senior author Brad Duchaine.
“This co-occurrence is likely due to the two abilities that depend on adjacent brain regions in the temporal lobe,” added Dr. Duchaine added.
When scientists ran tests to assess Annie’s problems with face recognition, they found that she found it particularly difficult to recognize familiar faces and learn the identities of unfamiliar faces.
In one of the tests, she was presented with 60 pictures of celebrity faces one after the other and asked to name them.
Annie was then presented with a list of the celebrities featured in the test to see if she knew them.
She correctly identified 29 percent of the 48 celebrities she was familiar with, compared to a control group who correctly identified 84 percent of known celebrities.
In another test, Annie was shown a celebrity’s name and then presented with pictures of two faces – one of a celebrity and the other of someone who looked like her.
She was able to identify the celebrity in 69 percent of the 58 trials, compared to 87 percent in the control group.
“Our results from the Unfamiliar Faces test show that not only could Annie not remember the name or biographical information of a famous person she knew, but she has real difficulty learning new identities,” said Dr. pebbles .
“It is known that there are wide-ranging cognitive problems that can be caused by Covid-19, but here we are seeing severe and very selective problems in Annie and that suggests there could be many other people who are quite severe and selective problems have post-Covid deficits,” added Dr. Duchaine added.
The researchers then obtained self-reported data from 54 people who had had Covid with symptoms for more than 12 weeks and 32 people who had reported fully recovering from the infection.
“One of the challenges that many respondents reported was the difficulty in visualizing family and friends, something we often hear from prosopagnostics,” said Dr. Duchaine.
The findings, the researchers say, highlight the perceptual issues in facial recognition and navigation that can be caused by Covid.
They call for future work to validate the findings and understand the nature of these visual deficits and determine whether interventions are needed to reduce their impact.