New research shows COVID-19 making us dumber with significant drops in IQ scores

New research indicates COVID-19 is making us dumber and leading to measurable cognitive decline. 

The study published in the New England Journal of Medicine found that even a mild infection with the virus leads to a fall in intelligence and it is worse if you have long-COVID or are hospitalised. 

Researchers at Imperial College London tested the cognitive ability of nearly 113,000 people who had previously had COVID-19. They found that those who had been infected had significant deficits in the ability to remember, reason and plan. 

Lead author Dr Adam Hampshire said the group with the largest cognitive deficit was on average people who were in intensive care. 

"They showed a difference of around about minus nine IQ points. People who have ongoing persistent symptoms, that is the ones who may have long COVID, they perform at about minus six IQ points and that's enough that it could have affected your daily function," he said.  

Seven IQ points was equivalent to aging 10 years. 

People who had been infected and no longer had symptoms also scored slightly lower than people who had never been infected, by the equivalent of three IQ points.

New Zealand epidemiologist, Professor Michael Baker, said those with COVID-19 have often talked about a feeling of brain fog.

"Some people describe it, yeah, as crippling brain fog and the fact that they do not feel that they can remember things very well or actually handle complex thought processes," he said. 

Prof Baker said after four years we were seeing evidence mounting and the case getting stronger, not weaker, that this was a virus that affected the brain severely, along with being a vascular disease.

He said most people were affected because they've now had the virus.

"We're all getting, unfortunately, a little less intelligent at a whole population level. That is devastating not just for us as people but also in terms of productivity and many other things," Prof Baker said. 

It could be brain damage that we can't get back with experts saying we will need to follow COVID-19 for many more years to know if there is any return to normal brain function, and warned that if you've had brain loss symptoms for more than a year then it's likely to be permanent.