“At Tufts University in Medford, Mass., researchers loaded a tiny 3D model of the human brain into a plastic shell resting atop a spring-loaded platform. Inside this polymer skull, the donut-shaped ball of living brain tissue floated in a warm, salty bath, its neurons whispering to each other in the darkness. Then a piston struck the platform, whipping it back and forth, and sending the mini-brain sloshing.

Days later, as the team assessed the damage, the results were stark. Some of the human brain-like tissue had been housing a latent infection with a herpes virus, the type that causes cold sores. And the impact of the piston — intended to mimic a concussion — had woken that virus up. In those tissues, the researchers found lots of inflammation, newly formed plaques of sticky amyloid proteins, and all around them dying neurons — the signature marks of Alzheimer’s disease. Meanwhile, infection-free brain tissues recovered from the concussion with just a bit of lingering inflammation. 

Decades of epidemiological data have shown that infections with herpes simplex virus type 1, or HSV-1 can raise the risk of Alzheimer’s disease in certain people. So can a history of head injury. The new research, published Tuesday in Science Signaling, is the first to connect the dots between them, and adds to mounting evidence that this most common form of dementia can be caused by an everyday microbe.”

From STAT.