Nikhil Prasad Fact checked by:Thailand Medical News Team Nov 09, 2025 2 hours, 26 minutes ago
Medical News: COVID-19 Spike Protein Causes Brain Damage and Memory Loss
A new study by researchers from the Korea National Institute of Health and Nexmos Inc. has uncovered how the spike protein of the SARS-CoV-2 virus may lead to brain damage, memory loss, and cognitive decline even after recovery from COVID-19. The study also found that the common diabetes drug metformin could protect the brain from these harmful effects.
Metformin Found to Protect Brain from COVID-19 Linked Damage
How the Spike Protein Reaches and Harms the Brain
The scientists discovered that when the spike protein enters the body, it can travel through the nasal passages into the brain—especially the hippocampus, a key area responsible for learning and memory. Once inside, the protein interferes with normal brain signaling, leading to inflammation, neuron loss, and accumulation of harmful proteins such as phosphorylated tau (p-tau) and α-synuclein, both linked to Alzheimer’s and Parkinson’s diseases. According to this
Medical News report, these changes disrupt communication between brain cells and reduce the brain’s ability to form or recall memories, mirroring symptoms commonly described as “brain fog” in long COVID patients.
Key Study Findings
In the experiment, the researchers administered a small amount of spike protein intranasally to laboratory rats. Within six weeks, the animals showed clear signs of memory impairment and anxiety. Genetic testing revealed that the spike protein altered the expression of genes vital for synaptic health, such as GRIN2A, SHANK1, and JPH3, leading to disrupted communication between neurons. The protein also triggered an abnormal activation of HIF-1α, a molecule normally linked to oxygen deprivation, which further suppressed brain cell function and promoted damage.
The study also confirmed that the spike protein directly caused the build-up of p-tau and α-synuclein—proteins that form toxic aggregates responsible for neurodegenerative diseases. Brain scans of the treated rats revealed neuron loss and enlargement of the brain’s ventricles, a sign of atrophy and deterioration.
Metformin’s Protective Effect
When the researchers treated the spike protein-exposed rats with metformin, they observed a reversal of many of these harmful effects. Metformin restored the normal activity of the genes responsible for maintaining synaptic function and reduced the buildup of toxic tau and α-synuclein proteins. It also appeared to block the spike protein’s ability to activate HIF-1α, preventing further damage to brain cells. These findings suggest that metformin could potentially be repurposed as a therapeutic option to prevent or treat long-term cognitive decline in post-COVID patients.
Why This Matters
This groundbreaking discovery adds new insight into how lingering viral proteins may continue to harm the brain even after recovery
from COVID-19. It also highlights how a readily available drug like metformin might help counteract these effects. The researchers emphasized that while the study was conducted in animals, the results closely mirror findings seen in human long COVID patients who experience persistent brain fog, memory loss, and confusion.
The study findings were published in the peer reviewed journal PLOS ONE.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0336015
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