COVID-19 survivors remain at higher risk of psychotic disorders, dementia and similar conditions for at least two years, according to a large study that highlights the mounting burden of chronic illness left in the pandemic’s wake.

While anxiety and depression occur more frequently after COVID-19 than other respiratory infections, the risk typically subsides within two months, researchers at the University of Oxford found. In contrast, cognitive deficits known colloquially as "brain fog,” epilepsy, seizures and other longer-term mental and brain health disorders remained elevated 24 months later, according to a study published Wednesday in the journal Lancet Psychiatry.

The findings, based on the records of more than 1.25 million patients, add to evidence of the virus’s potential to cause profound damage to the central nervous system and exacerbate the global burden of dementia — which cost an estimated $1.3 trillion in the year the pandemic began. Oxford researchers showed in March that even a mild case is associated with brain shrinkage equivalent to as much as a decade of normal aging.