A new study has stated that people who have had a case of Covid-19, no matter how benign, may experience brain aging and even an increased risk of dementia or Alzheimer's disease.
The study, published Monday, March 7 in the journal Nature, would be the largest of its kind and it found that the brains of those who had had Covid-19 had greater loss of gray matter and abnormalities in brain tissue compared to those who did not have Covid-19. The study showed that many of these changes affected the area of the brain related to smell.
"We were quite surprised to see clear differences in the brain even with a mild infection," said lead author Gwenaëlle Douaud, associate professor of neuroscience at the University of Oxford.
Dr. Douaud and his colleagues checked brain imaging photos of 401 people with Covid-19 between March 2020 and April 2021, both before infection and on average 4 and a half months after infection.
They compared the results of these people with brain imaging of 384 uninfected people similar in age, socio-economy and risk factors such as blood pressure and obesity. Of the 401 people infected, 15 had been hospitalized. Douaud explained that it's normal for people to lose 0.2% to 0.3% of gray matter each year in memory-related areas of the brain as they age, but in the study's assessment, people who had been infected with the coronavirus lost an extra 0.2% to 2% of tissue compared to those who had not been infected, a surprising discovery.
In addition to imaging, study participants were tested for executive and cognitive function. Using the Trail Making Test, participants were tested for cognitive impairment associated with dementia and tests of speed and brain function. The researchers found that those with the greatest loss of brain tissue also had the worst results on this exam.
"Since the abnormal changes we observe in the brains of infected participants could be partly related to their loss of smell, it is possible that its recovery will lead to these brain abnormalities becoming less pronounced over time. Similarly, it is likely that the harmful effects of the virus (whether direct or indirect via inflammatory or immune reactions) will decrease over time after infection. The best way to find out would be to scan these participants again in one or two years," she said
Douaud added that the researchers plan to reimage and test participants in one or two years. And while the study finds some association between infection and brain function, it's still unclear why. The authors cautioned that the findings were only one-off, but noted that they "raise the possibility that the longer-term consequences of SARS-CoV-2 infection may ultimately contribute to Alzheimer's disease or other forms of dementia."
0 Comments