Researchers found that deficits equivalent to six IQ points were detectable a year or more after infection

People experiencing long Covid have measurable memory and cognitive deficits equivalent to a difference of about six IQ points, a study suggests.

The study, which assessed more than 140,000 people in summer 2022, revealed that Covid-19 may have an impact on cognitive and memory abilities that lasts a year or more after infection. People with unresolved symptoms that had persisted for more than 12 weeks had more significant deficits in performance on tasks involving memory, reasoning and executive function. Scientist said this showed that “brain fog” had a quantifiable impact.

Prof Adam Hampshire, a cognitive neuroscientist at Imperial College London and first author of the study, said: “It’s not been at all clear what brain fog actually is. As a symptom it’s been reported on quite extensively, but what our study shows is that brain fog can correlate with objectively measurable deficits. That is quite an important finding.”