Most people recover from COVID-19 within a few weeks of symptom onset. However, some experience long-term complications that last several weeks or months, a phenomenon previously referred to as “long COVID” and now known as “post-acute sequelae after SARS-CoV-2 infection,” or PASC, characterized by chronic fatigue, brain fog, and other neurocognitive symptoms.
Scientists don’t fully understand what causes PASC, but viral persistence, chronic inflammation, hypercoagulability, and autonomic dysfunction likely play roles. A recent study links these drivers to a single cause: low serotonin levels.
Researchers analyzed the blood of participants enrolled in a long-term study of COVID-19 and PASC. They found that the participants had low serotonin levels post-infection, and those levels predicted whether a person recovered fully or developed PASC.
Then, using a mouse model of COVID-19, they demonstrated that viral inflammation altered genetic pathways regulating serotonin absorption in the gut – the primary source of the body’s serotonin. They also showed that serotonin depletion impairs vagal nerve activity, in turn reducing hippocampal activity and driving neurocognitive dysfunction. Giving the mice a selective serotonin reuptake inhibitor (SSRI, a drug that promotes serotonin uptake in the gut) improved their cognitive function.
These findings suggest that low serotonin levels drive the symptoms associated with PASC and highlight the potential for SSRI treatment following COVID-19 illness. Learn about the symptoms of PASC (“long-haul COVID”) in this clip featuring Dr. Roger Seheult.
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