Sao Paulo, Aug 18 : Patients with the most severe post-Covid smell and taste problems tend to do worse in cognitive tests, particularly when they are related to memory, says research that confirms that the loss of smell may be a indication of the development of Alzheimer’s disease. The study involved a team of Brazilian researchers examined the clinical information of 701 patients who were hospitalised for severe or moderate Covid-19.
The findings, published in the European Archives of Psychiatry and Clinical Neuroscience and Clinical Neuroscience, revealed that a moderate or severe reduction in sensation of taste as the most frequently-reported sensory complications (20 percent) followed by a severe or moderate sensory deficit (18 percent) and the presence of a severe or moderate deficit of both taste and smell (11 percent) and parosmia (9 percent) or distortion of the sense of smell, meaning that a smell previously enjoyed is now unpleasant, for instance.
Odor hallucinations (perceiving scents of which other people were not aware) were reported by 12 of the participants, as well as hallucinations of the gustatory (perceiving tastes, but not eating food) in nine.
In both instances, the majority reported that hallucinations took place only after the Covid experience.
People who have parosmia (smell loss that is linked with Covid) are found to suffer more memory issues than the restof us, while those with moderate or extreme loss of taste had significantly less.
The people who reported significant or moderate loss of both taste and smell were also found to be impaired memory for episodic events.
“We did not observe any psychiatric signs (such as depression or anxiety) to be connected with loss of smell or taste however, as we expected, we found that episodic memory and attention were less effective in people with more chemosensory disturbances,” said Rodolfo Damiano doctoral student at the University of Sao Paulo’s Medical School (FM-USP) in Brazil.
“This discovery supports the idea that Covid affects cognition and that the damage in this region doesn’t just result from environmental or psychosocial causes.”
The loss of smell stems from the inflammation caused by SARS-CoV-2 in the mucosa olfactory the team stated.
The cognitive declines that are observed in Alzheimer’s and post-Covid syndromes result from different pathogenic processes, however they may also overlap, as explained by the psychogeriatrician, Orestes Forlenza who is Professor in FM-USP’s Psychiatry Department.
“This is especially the case in older individuals who have already experienced primary cognitive impairments and who contract Covid.
There is evidence to suggest that this overlap of pathogenic factors could accelerate or accelerate the process of cognitive decline,” he said.
However the exact mechanism that leads to cognitive impairment in Covid patients is not known.
“Our theory is that the virus causes neuroinflammation which causes cognitive impairment.We aren’t sure whether the injury is irreparable.We’ll keep monitoring the patients to determine if these complications resolve,” Damiano said.
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