Scientists have identified molecular signatures in the blood that are linked to brain fog, other cognitive problems and fatigue in patients who are diagnosed with long Covid<\/a> after catching the virus.<\/p>\n\n\n\n Raised levels of two different proteins were more common in people who developed long Covid symptoms that affected their brains, the researchers found. Both are hallmarks of blood clots in the body, the likely cause of the symptoms reported.<\/p>\n\n\n\n The work, described as \u201can important step forward\u201d by one independent expert, bolsters thinking that emerged at the height of the pandemic that Covid leaves some patients with tiny clots in their lungs, and potentially in their brains, leading to a wide range of long-term memory, concentration and thinking problems.<\/p>\n\n\n\n The findings could prove useful if clinical trials such as Stimulate-ICP<\/a>, which are testing a range of treatments for long Covid, conclude that anticoagulants can improve brain fog and fatigue in some patients. Testing patients\u2019 blood protein levels could alert doctors to those who should be treated for clots early and those who are less at risk.<\/p>\n\n\n\n The researchers looked at blood proteins in more than 1,800 hospitalised Covid patients and found that at the time of infection, those who went on to develop long-lasting cognitive problems were more likely than others to have raised levels of a protein called fibrinogen, or a protein fragment called D-dimer.<\/p>\n\n\n\n High levels of fibrinogen are a sign of blood clots in the body. According to Max Taquet, an author on the study at the University of Oxford, patients could have blood clots on the brain that cause cognitive problems, or fibrinogen itself could be affecting the brain.<\/p>\n\n\n\n Raised levels of D-dimer also signify blood clots in the body, but patients with high concentrations of the protein also tended to have post-Covid fatigue and breathlessness, leading the researchers to suspect blood clots on the lungs which can reduce blood flow to the brain and also cause fatigue.<\/p>\n\n\n\n \u201cIndividuals with elevated D-dimer levels were not only more prone to brain fog but also displayed a heightened risk of respiratory challenges,\u201d Taquet said.<\/p>\n\n\n\n Danny Altmann, a professor of immunology at Imperial College London, and a leading long Covid expert, said: \u201cThis is an important step forward in our understanding of the stratification of Long Covid<\/a> and, potentially, some of the underlying mechanisms \u2013 they argue the case in support of possible input from effects on clotting pathways.\u201d<\/p>\n\n\n\n While a blood test to look for raised levels of the proteins could help doctors flag Covid patients most likely to develop brain fog and other long Covid symptoms, the biomarkers will not spot all patients at risk.<\/p>\n\n\n\n \u201cReal care is needed,\u201d said Dr Michael Zandi at UCL\u2019s Queen Square Institute of Neurology. \u201cThe associations do not give us yet a clear one-size-fits-all mechanism, and treatments need to pass through rigorous clinical trial first.\u201d<\/p>\n\n\n\n![\"Tired](\"https:\/\/i.guim.co.uk\/img\/media\/ba1c43882ef345d22532962e80c77ec0ee3a3e5a\/0_193_7952_4771\/master\/7952.jpg?width=460&quality=85&auto=format&fit=max&s=368938ba111a4a384261cc81228418f1\")
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