🧠 Alzheimer’s may not be caused by brain decay but the immune system misfiring. A bold new theory

🧠 Alzheimer’s may not be caused by brain decay — but the immune system misfiring.

A bold new theory is reshaping our understanding of Alzheimer’s disease: it might not be caused by degenerating brain cells, but by the brain’s own immune system turning against itself.

Dr. Donald Weaver at the Krembil Brain Institute proposes that beta-amyloid—a protein long blamed for Alzheimer’s—is not a harmful byproduct, but an immune molecule meant to protect the brain. Under this model, beta-amyloid responds to perceived threats like infection or injury.
The twist? Because neurons and bacteria have similar fatty membranes, the immune system may start mistaking brain cells for invaders.

Over time, this misfiring immune response could become chronic, leading to the cognitive decline and memory loss that define Alzheimer’s. If true, the disease may actually be a form of autoimmune disorder—where the brain wages war on itself. This insight could explain why decades of anti-amyloid drugs have repeatedly failed: they treat a symptom, not the root cause. Researchers like Weaver argue that future therapies should focus on calming the brain’s immune system, not just eliminating beta-amyloid. It’s a shift that could redefine the path to effective prevention and treatment.

source
Source: Weaver, D. (Krembil Brain Institute).