Risk of ‘brain fog’ still high two years after catching Covid-19

Millions of people who have had Covid-19 still face a higher risk of neurological and psychiatric conditions including ‘brain fog’, epilepsy and dementia two years after catching the virus, an Oxford University study has found.

They also face a higher risk of anxiety and mood disorders such as depression; however, this risk subsides within two months of having the coronavirus, according to the study published in The Lancet Psychiatry journal.

Researchers assessed the risks of 14 neurological and psychiatric diagnoses after Covid-19 infection, compared with other respiratory illnesses.

The study involved an analysis of anonymised data relating to patients who contracted Covid-19 between January 2020 and April 2022. The data was collected from hospitals, primary care providers and specialist care services in the UK, US, Australia, Spain, Bulgaria, India, Malaysia and Taiwan.

Demographic factors, risk factors for Covid-19 and severe Covid-19 illness, and vaccination status were considered. The analysis was broken down by age group and date of diagnosis.

Risks of developing cognitive deficit, more commonly known as “brain fog”, and other neurological or psychiatric conditions such as dementia, epilepsy, seizures and psychotic disorders, were still elevated at the end of the two-year follow-up period.

A sizeable proportion of older adults who received a neurological or psychiatric diagnosis subsequently died, especially those diagnosed with dementia or epilepsy or seizures.

The levels of risk were similar before and after the emergence of the alpha variant. However, risk of ischaemic stroke, epilepsy or seizures, cognitive deficit, insomnia, and anxiety disorders were increased after delta emerged, compounded by an increased death rate.

With omicron there was a lower death rate than just before emergence of the variant, but the risks of neurological and psychiatric outcomes remained similar.

Dr Max Taquet, co-author of the study, said: “Our findings shed new light on the longer-term mental and brain health consequences for people following Covid-19 infection.

“It is good news that the higher risk of depression and anxiety diagnoses after Covid-19 is relatively short-lived and there is no increase in the risk of these diagnoses in children. However, it is worrying that some other conditions, such as dementia and seizures, continue to be more frequently diagnosed after Covid-19, even two years later.”

A recent study in the Netherlands found that one in eight people who caught Covid-19 went on to experience long Covid symptoms, including chest pain, painful muscles and general tiredness.