Scientists decode how Covid triggers brain fog

The coronavirus pandemic continues to have a lingering effect on the world as scientists scramble to understand the many long-lasting effects of the virus.

One such is a condition that has cognitive effects like memory loss and difficulty learning, known as brain fog. it leads to a feeling of mental confusion, lack of clarity, or difficulty concentrating. It can manifest as forgetfulness, trouble remembering information, inability to focus, and overall cognitive sluggishness.

Researchers at the University of Illinois Chicago have now identified the mechanism that causes this neurological condition. The findings are based on a study in mice, which were infected with SARS-CoV-2, the virus behind Covid-19.

Mice is used in neurological studies due to their many genetic, physiological, and behavioural similarities with humans, making them valuable models for studying human neurological disorders and diseases.

The details published in the journal Brain reveal that researchers focused on the blood-brain barrier, which plays a role in other neurological diseases, such as multiple sclerosis.

The team said that normally, this barrier protects the brain from potentially harmful cells or molecules circulating in the bloodstream. But the infected mice, researchers found, had leaky blood-brain barrier vessels and impaired memory or learning.

This research suggests that improving blood-brain barrier integrity could have benefits. (Photo: AFP)
Researchers looked at blood vessels from the brains of infected mice to see which genes were most altered and found a significant decrease in a signalling pathway called Wnt/beta-catenin, which helps maintain the health of the blood-brain barrier and protects the brain from damage.

The team focussed on older mice in the study to better understand risk factors for cognitive impairment in older people infected with Covid-19. They specifically tracked mild infections in the mice. Mild, rather than severe, infections account for most Covid-19 cases in humans today post-vaccination.

This research suggests that improving blood-brain barrier integrity could have benefits in preventing complications of Covid-19. One major lesson from the Covid-19 pandemic is that even mild infections can profoundly affect organs, including the brain.