After studying brain scans and cognitive tests on 785 UK Biobank participants – out of which 401 had been infected with the virus – researchers could identify symptoms like a greater loss in grey matter volume in the cerebral cortex of the brain of Covid patients.
The results showed that four and a half months after a mild Covid infection, patients had lost (on average) between 0.2 and 2% of brain volume, as compared to healthy people.
In addition to this, they also took between 8 and 12% longer on the tests that measured attention, visual screening ability, and processing speed.
In the region of the brain linked to smell, the Covid-19 patients had 0.7% more tissue damage compared to healthy people.
This is part of a growing body of research that suggests that people who have recovered from Covid-19, including patients with milder symptoms, may struggle with cognitive functions.
Recently, a study published in the journal eClinicalMedicine suggested that a severe Covid-19 infection may cause cognitive impairment similar to that sustained with 20 years of ageing, between 50 and 70 years of age. This is equivalent to losing about 10 IQ points.
The study analysed 46 Covid-19 patients who received in-hospital care, on the ward or intensive care unit, for six to ten months. Out of the total, 16 patients were put on mechanical ventilation during their stay in the hospital.
After detailed computerised cognitive tests, the researchers were able to detect that the patients showed slower and less accurate responses than what was expected for their age and demographic profile.
Those patients who required ventilators and organ support scored even worse.
Survivors scored particularly poorly on tasks such as verbal analogical reasoning, a finding that supports the commonly-reported problem of difficulty finding words.
They also showed slower processing speeds, which aligns with previous observations post Covid-19 of decreased brain glucose consumption within the frontoparietal network of the brain, responsible for attention, complex problem-solving and working memory, among other functions.
