For those who have contracted COVID and lost their sense of smell, life hasn’t exactly been a bed of roses. And sadly, for that group, the news appears to be getting worse.
The latest research suggests those in that group are more likely to suffer from long-term memory problems and other cognitive impairment issues.
From the evidence gathered, it appears a persistent loss of smell is a better predictor of lingering cognitive symptoms after COVID than the actual severity of the disease itself.
Read: How the travel industry uses your sense of smell to enhance your trip
The supporting evidence comes from new research done at the at the Pontifical Catholic University of Argentina in Buenos Aires. A research team led by Gabriela Gonzalez-Alemán analysed data from 766 adults aged 60 or older who had no history of cognitive impairment. Each had taken a PCR test at a COVID testing clinic, and nearly 90 per cent of those tested returned a positive result.
Each participant had data collected regarding the severity of their symptoms and completed a sniff test, followed by a series of cognitive assessments at least three months after the COVID test.
Collated results showed that around two-thirds of those who had tested positive for COVID had at least some form of memory impairment and, of those, half said it was severe enough to interfere with their daily lives.
Read: What’s causing my loss of smell and taste?
The results reinforced previous evidence of a loss of smell being a predictor of ongoing health problems. A study published earlier this year found that olfactory deficit (loss of smell) could be an early warning sign of Alzheimer’s disease.
Dr Gonzalez-Alemán and her team found the people who still had complete loss of smell three months post-infection were roughly 1.5 times more likely to have lasting cognitive impairment compared with those who never lost or had already regained their sense of smell. Again, this was the case regardless of the severity of their infection or whether they had been hospitalised.
As well as being a predictor of long-term cognition problems, these results provide a potential clue to the way COVID makes its way into the brain.
Most brain cells lack the ACE2 receptor the virus normally uses to break into cells.
Read: Our sense of smell helps keep us alive, new research finds
Coronavirus can infect cells in the nose, and the resulting inflammation of these cells can disrupt scent-detecting olfactory neurons resulting in the loss of smell. The virus might then build tiny tunnels in nose cells and shuttle through these to infect brain cells.
This would provide one possible explanation for the link between loss of smell and some cognitive symptoms.
Dr Gonzalez-Alemán and her colleagues plan to run follow-up research on the 766 participants. Over a four-year period, they hope to learn more about the long-term effects of COVID infection on cognition, and better understand the mechanism linking the sense of smell with memory problems more broadly.
Did you lose your sense of smell when you had COVID? How has it affected you? Why not share your experience and thoughts in the comments section below?
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