Alzheimer’s disease, which affects more than 55 million people worldwide, may be driven not only by toxic protein buildup in the brain but also by imbalances in the body’s adaptive immune system, according to a new review.
Researchers from Fujian Medical University Union Hospital and the Fujian Key Laboratory of Molecular Neurology in China found that T and B cells, key components of adaptive immunity, can cross the weakened blood–brain barrier in Alzheimer’s patients.
Once inside the brain, these cells act in complex ways: some release inflammatory molecules that worsen nerve damage, while others appear to help protect brain tissue and clear toxic proteins.
“Adaptive immunity acts like a double-edged sword,” lead researcher Dr Xiaochun Chen said. “Some immune cells may accelerate memory loss, while others provide a protective role. Learning to tip the balance is crucial for future treatment.”
The findings, published August 5, 2025, in the Chinese Medical Journal, suggest that Alzheimer’s is not only a disease of plaques and tangles but also of immune imbalance. Current treatments targeting amyloid proteins, such as aducanumab and lecanemab, have delivered mixed results, but scientists believe therapies that also rebalance immune responses could prove more effective.
The review highlights the potential for new approaches, including vaccines or therapies tailored to patients’ genetic risk factors. Researchers say further studies are needed to understand how immune cells enter the brain and why their effects vary among patients.
