After years of uncertainty, researchers in Japan have identified a clear biological cause behind Long COVID’s most persistent symptom: brain fog. The discovery could pave the way for accurate diagnosis and, for the first time, real treatment options. Here’s what scientists uncovered.
The puzzle of brain fog
Up to 80% of people with Long COVID experience brain fog — confusion, poor focus, and memory problems that can last months or even years.
Millions are affected worldwide
With hundreds of millions of COVID-19 cases globally, Long COVID’s cognitive effects pose an ongoing health and economic challenge.
Until now, the cause was invisible
Previous scans revealed small changes in brain structure, but no one could explain why patients’ thinking and memory were so disrupted.
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A new kind of brain scan changed everything
Scientists at Yokohama City University used a groundbreaking PET imaging method to visualize AMPA receptors — molecules that help brain cells communicate.
More receptors, more brain fog
The scans revealed unusually high AMPA receptor density in patients with Long COVID, directly tied to how severe their symptoms were.
A biological fingerprint of the disease
The findings show that brain fog isn’t “just in your head.” It’s a measurable, molecular condition with a clear biological signature.
Inflammation plays a major role
Higher AMPA levels were linked to inflammation markers in the blood, suggesting that the immune system may drive these brain changes.
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Memory and learning are directly affected
Because AMPA receptors control information flow between neurons, their overactivity may explain problems with attention, memory, and focus.
The brain can now be clearly distinguished
Researchers were able to identify Long COVID patients with 100% sensitivity and 91% specificity — a major breakthrough for diagnosis.
A new path for treatments
Targeting AMPA receptor activity could become a future therapy, potentially restoring normal brain function in affected individuals.
Proof that brain fog is real
The study provides scientific validation that Long COVID brain fog is not psychological but biological — a condition that deserves serious medical attention.
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This article is based on information from ScienceDaily
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