10/07/2025
🧠 Long COVID brain fog finally has a scientific explanation
For years, millions of people suffering from Long COVID have reported “brain fog”—trouble with memory, focus, and thinking clearly. Now, researchers in Japan have identified a biological cause behind these cognitive struggles.
A team at Yokohama City University used an advanced brain imaging technique called [11C]K-2 PET scanning to reveal abnormal increases in AMPA receptors (AMPARs)—molecules crucial for learning and memory—in patients with Long COVID. Elevated AMPAR levels were directly linked to both the severity of brain fog and higher inflammation markers, providing the first clear molecular evidence of the condition.
Published in Brain Communications (Oct 2025), the study found that AMPAR density could distinguish affected individuals from healthy ones with remarkable accuracy—100% sensitivity and 91% specificity. This breakthrough opens the door to new diagnostic tools and potential treatments, such as drugs targeting AMPAR activity.
With brain fog affecting over 80% of Long COVID patients worldwide, this discovery is a vital step toward validating patients’ experiences and accelerating the search for effective therapies.
📖 Reference: Yu Fujimoto et al., Systemic increase of AMPA receptors associated with cognitive impairment of long COVID, Brain Communications, 1 October 2025.
