The identification of a metabolic pathway could lead to answers and new treatments for those experiencing brain fog because of long COVID. Researchers from UNSW Sydney and St Vincent’s Hospital have identified a key pathway, involved in inflammation, which appears to be activated in people with long COVID who have symptoms of ‘brain fog’. Scientists from the School of Psychology and Faculty of Medicine & Health found that of the study cohort of 128 people, those who had a prolonged activation of the kynurenine pathway were more likely to have had mild cognitive deficits 12 months after developing COVID-19. They also found that these symptoms were less likely to improve over time. Patients who took part in this study had mild-to-moderate acute COVID-19 and were enrolled in the St Vincent’s COVID-19 ADAPT study, a longitudinal study led by Prof Gail Matthews. The study, published in Annals of Clinical and Translational Neurology, helps demonstrate that there is a biological change underlying brain fog in people who have long COVID. “I think when patients go to the doctor’s with brain fog, it may be dismissed as a psychological problem,” said lead study author A/ Prof Lucette Cysique. “Our study speaks to the contrary, that there is a real biological mechanism behind long COVID brain fog.” The discovery opens up possibilities for identifying and treating people who are experiencing the cognitive or general effects of long COVID. “These findings lay the foundation for the kynurenine pathway as a potential diagnostic and monitoring marker, as well as a possible therapeutic target,” A/Prof. Cysique explained.