Clues to Brain Fog Found in Long Covid Patients

Oct 01, 2025 | News On Japan

TOKYO - A new study has shed light on the lingering condition known as brain fog, one of the most troubling aftereffects of Covid-19. Researchers at Yokohama City University found that patients experiencing this symptom showed higher levels of a key brain protein compared to healthy individuals, suggesting a potential pathway for future treatment.

Post-Covid symptoms can include fatigue, loss of taste, and a persistent mental haze commonly referred to as brain fog, in which patients report difficulty thinking clearly. Diagnosis of these aftereffects remains challenging, and no established treatment currently exists.

The Yokohama team analyzed the brains of 30 patients who reported brain fog symptoms using a specialized CT imaging technique known as PET scans. The study revealed that all 30 patients had elevated levels of AMPA receptors, proteins essential for information transmission in the brain, compared to those without the condition.

“The colored regions show areas where AMPA receptors are abundant, and we see increases across the entire brain,” said Takaya Takahashi, professor at Yokohama City University’s School of Medicine. “This finding gets us closer to the essence of brain fog’s pathology.”

According to Takahashi, the excessive density of AMPA receptors may disrupt information processing in the brain, leading to the cognitive cloudiness patients describe. The research group now plans clinical studies using drugs designed to suppress AMPA receptor activity.

“Brain fog is often misunderstood and dismissed as being in someone’s imagination,” Takahashi said. “Our study clearly shows that abnormal processes are taking place in the brain, and we now have a foothold for developing diagnostic methods and treatments.”

The findings were published in the scientific journal Brain Communications.

Source: TBS

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