Many people who have long COVID—a condition in which health issues persist months after infection—report struggling with “brain fog,” recurring memory and concentration lapses that make it difficult to function in everyday life. Now a new study has found these cognitive problems could result from blood clots triggered by infection, possibly through mechanisms like those that cause some types of dementia. These clots leave telltale protein signatures in blood, suggesting that testing for them could help predict, diagnose and possibly even treat long COVID.
The findings, published on Thursday in Nature Medicine, suggest that existing blood tests for detecting these proteins could help physicians recognize long COVID (although some experts caution that long COVID’s symptoms and causes likely vary among individuals). Up to 15 percent of people who contract SARS-CoV-2, the virus that causes COVID, go on to develop long COVID symptoms that can last for months or years. The condition has proved difficult to treat—or even diagnose—because of the mishmash of reported symptoms such as brain fog, fatigue, respiratory problems and numerous other effects. It’s still unclear whether the virus sticks around in the body or the initial infection triggers another reaction, such as an autoimmune response, that leads to the continuing symptoms.
To look into this question, lead study author and psychiatrist Maxime Taquet of the University of Oxford followed more than 1,800 people in the U.K. who were hospitalized for COVID between 2020 and 2021. Taquet and his colleagues checked in with the patients six and 12 months after their initial infection to monitor any prolonged symptoms and give them a cognitive test designed to diagnose disorders such as Alzheimer’s.
