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."
The new study is very small and more research is required to confirm the findings. But it highlights the importance of developing drugs that could target both amyloid and tau buildup, something researchers hope one day could help healthy but at-risk people stave off the earliest symptoms of Alzheimer's.
This is exactly the type of information we're going to need" for better treatments, said Alzheimer's Association chief science officer Maria Carrillo, who wasn't involved in the new study. "It's cool to see the utility of this new imaging technology actually being deployed and used."About 5 million people in the U.S. are living with Alzheimer's, a number expected to more than double by 2050 as the population ages. Today's medications only temporarily ease symptoms, and finding new ones is complicated by the fact that Alzheimer's quietly ravages the brain a decade or two before symptoms appear.