New study suggests alzheimer’s may start outside the brain

The widely held belief that Alzheimer's disease begins inside the brain is being challenged by new research. Scientists now suggest the disease might be triggered by external threats, based on genetic risk factors linked to blood vessels and immune cells forming the brain's boundary.

Understanding how Alzheimer's starts is crucial to finding effective treatments. While most research has focused on neurons inside the brain, a new study by scientists from the U.S. and Germany suggests the real trigger could lie at the brain's borders.

NEUROSCIENTIST ANDREW YANG FROM THE GLADSTONE INSTITUTE OF NEUROLOGICAL DISEASE STATED:

"When studying brain diseases, most research focuses on neurons. We hope our findings draw more attention to the cells at the brain's boundaries, which may play a central role in diseases like Alzheimer's."

GENETIC VARIANTS FOUND AT THE BRAIN BARRIER

Researchers developed a new genetic analysis technique called MultiVINE-seq, allowing them to examine blood vessel and immune cells from the brain tissues of 30 deceased individuals. The analysis revealed that many genetic variants previously linked to neurological diseases were present in cells that protect the brain's boundaries — particularly endothelial cells (which regulate brain access) and T cells from the immune system.

These genetic variants may cause inflammatory immune cells to trigger or accelerate Alzheimer's. Neuroscientist Madigan Reid explained:
"We knew these variants increased disease risk, but didn't know how they behaved in the brain's barrier cells. Our study shows many of them function in blood vessels and immune cells."

A NEW HOPE FOR TREATMENT

This discovery suggests Alzheimer's may not be solely due to protein build-up inside the brain, but potentially also triggered by external threats. This new perspective could lead to more accessible drug targets and lifestyle interventions.

Researchers say this work brings blood vessel and immune cells to the forefront and could offer a new roadmap for protecting the brain from the outside in.