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COVID increases risk of brain fog and dementia, study suggests

Disorders such as psychosis, dementia, seizures, and brain fog remain more common for as much as two years after COVID-19 infection than after other respiratory infections, a study finds.

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People who have had COVID face a higher risk of developing neurological and psychiatric conditions like psychosis, dementia and brain fog as much as two years after infection - compared with those who have had other respiratory illnesses, new research suggests.

Adults also face an increased risk of anxiety and depression, but this subsides within two months of their illness, researchers found.

The study of 1.25 million people diagnosed with coronavirus also found children are more likely to be diagnosed with some conditions, like seizures and psychotic disorders.

However, the likelihood of most diagnoses after having COVID-19 was lower than in adults.

The study analysed data on 14 neurological and psychiatric diagnoses gathered from electronic health records mostly from the US over a two-year period.

It found that in adults, the risk of depression or anxiety increased after COVID-19, but returned to the same as with other respiratory infections within about two months.

However, the risk of being diagnosed with some other neurological and mental health conditions remained higher after coronavirus than for other respiratory infections at the end of the two-year follow-up.

More on Covid-19

Adults aged 64 and under had a higher risk of brain fog, and muscle disease, compared with those who had other respiratory infections.

In adults aged 65 and over who had COVID there was a higher occurrence of brain fog (1,540 cases per 10,000 people), dementia (450 cases per 10,000 people) and psychotic disorder (85 cases per 10,000 people) compared with those who previously had a different respiratory infection.

Researchers found the Delta variant was associated with more disorders than the Alpha, and Omicron with similar neurological and psychiatric risks as Delta.

Professor Paul Harrison, from the University of Oxford and lead author of the study published in The Lancet Psychiatry, said while the numbers are not trivial, they are not huge and need to be set against the increasing burden of brain and mental health problems that may have occurred in the whole population because of the pandemic.

He said: "In addition to confirming previous findings that COVID-19 can increase the risk for some neurological and psychiatric conditions in the first six months after infection, this study suggests that some of these increased risks can last for at least two years.

"The results have important implications for patients and health services as it suggests new cases of neurological conditions linked to COVID-19 infection are likely to occur for a considerable time after the pandemic has subsided.

"Our work also highlights the need for more research to understand why this happens after COVID-19, and what can be done to prevent or treat these conditions."