Restoring Serotonin Signaling in Long COVID
MAAYAN LEVY, MD
Stanford University (previously Perelman School of Medicine, University of Pennsylvania)
Foundational Discovery
Dr. Levy's lab made a landmark discovery — published in Cell in 2023 — demonstrating that Long COVID patients exhibit a persistent reduction in circulating serotonin levels. The team identified the mechanism: residual SARS-CoV-2 viral RNA in the gastrointestinal tract (detected in roughly 30% of Long COVID patients) drives chronic interferon responses that suppress gut production of serotonin. Reduced serotonin impairs vagal nerve signaling to the brain, contributing to the neurocognitive symptoms — brain fog, memory impairment, fatigue — that define Long COVID.
In preclinical models, the team demonstrated that serotonin levels could be restored and memory impairment reversed through treatment with serotonin precursors or SSRIs — establishing the therapeutic rationale for the clinical trial now underway.
The serotonin pathway in Long COVID
Viral persistence: Residual SARS-CoV-2 RNA in the GI tract triggers sustained interferon signaling long after acute infection resolves.
Serotonin depletion: Chronic inflammation suppresses enteroendocrine cell production of serotonin — the only major metabolite that fails to recover in Long COVID patients.
Neurocognitive symptoms: Reduced serotonin impairs vagal nerve signaling, disrupting brain function and producing brain fog, memory loss, and cognitive fatigue.
Key Publications:
Serotonin reduction in post-acute sequelae of viral infection
From intestinal metabolites to the brain: investigating the mysteries of Long COVID
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