Washington - Scientists are peeking inside living brains to watch for the first time as a toxic duo of plaques and tangles interact to drive Alzheimer’s disease — and those tangles may predict early symptoms, a finding with implications for better treatments.

It’s not clear exactly what causes Alzheimer’s. Its best-known hallmark is the sticky amyloid that builds into plaques coating patients’ brains, but people can harbor a lot of that gunk before losing memories.

Now new PET scans show those plaques’ co-conspirator — the tangle-causing protein tau — is a better marker of patients’ cognitive decline and the beginning of symptoms than amyloid alone. That’s especially true when tau spreads to a particular brain region important for memory, researchers reported Wednesday in the journal Science Translational Medicine.

“It’s a location, location, location kind of business,” said Dr. Beau Ances of Washington University in St. Louis, who led the work. The plaque “starts setting up the situation, and tau is almost the executioner.”... Read More: VIN