While it is well known that Covid-19 can cause a wide range of neurological problems, such as the loss of taste and smell, as well as impairments in memory, attention, speech, and language – commonly referred to as “brain fog” – a new study led by Dartmouth College has recently found that it could also cause prosopagnosia, or “face blindness,” a condition characterized by difficulty in recognizing familiar faces and navigational problems.
The experts worked with Annie, a 28-year-old woman who was diagnosed with Covid-19 in March 2020 and experienced a symptom relapse two months later. Shortly after, she started having difficulties with recognizing the faces of her family members, as well as spatial navigation issues, including problems remembering where particular sections in her grocery store were located or where she parked her car.
“The combination of prosopagnosia and navigational deficits that Annie had is something that caught our attention because the two deficits often go hand in hand after somebody either has had brain damage or developmental deficits,” explained study senior author Brad Duchaine, a professor of Psychological and Brain Sciences at Dartmouth. “That co-occurrence is probably due to the two abilities depending on neighboring brain regions in the temporal lobe.”
The scientists conducted a series of tests with Annie to assess her deficits. In one of them, after being presented with 60 images of celebrity faces, she managed to correctly identify 29 percent of those she was familiar with, compared to people in a control group who managed to identify 84 percent of the familiar celebrities. In another, she was shown a celebrity’s name and was asked to identify that celebrity’s face from an image of the celebrity and one of someone similar, and succeeded in 69 percent of the cases, compared to the 87 percent success rate in the control group. Finally, after she was asked to learn six men’s faces and then distinguish between them and other faces – in a so-called Cambridge Face Memory Test – she managed to do this in only 56 percent of the cases, compared to the 80 percent success rate of people without prosopagnosia.
“Our results from the test with unfamiliar faces show that it wasn’t just that Annie couldn’t recall the name or biographical information of a famous person that she was familiar with, but she really has trouble learning new identities,” said lead author Marie-Loise Kieseler, a graduate student in Psychology and Brain Sciences at Dartmouth.
To assess whether other people who had Covid-19 experienced similar problems, the researchers obtained data from nearly 100 individuals with long Covid. “Most respondents with long Covid reported that their cognitive and perceptual abilities had decreased since they had Covid, which was not surprising, but what was really fascinating was how many respondents reported deficits,” Kieseler said. “It was not just a small concentration of really impaired cases but a broad majority of people in the long Covid group reported noticeable difficulties doing things that they were able to do before contracting Covid-19 without any problems.”
Although none of these respondents seemed to have the severity of Annie’s symptoms, the scientists are sure that similar cases must exist, and urge individuals experiencing perceptual or vision problems possibly caused by Covid to contact them.
The study is published in the journal Cortex.
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