Researchers at the University of California, Riverside (UCR) say the earliest changes could instead happen inside nerve cells, where two key proteins appear to interfere with each other. 

For years, much of the focus has been on amyloid beta, or a-beta, because it forms clumps in the brains of people with Alzheimer's. That link appeared well supported, especially since genetic mutations that increase a-beta levels are known to cause early-onset forms of the disease. 

But attempts to treat Alzheimer's by removing these clumps have been largely unsuccessful, with thousands of trials failing to stop or reverse its progression. 

Michael Kane, chief medical officer at Indiana Center for Recovery, told Newsweek that the findings of this study should not be seen as dismissing the amyloid theory entirely, but rather as refining it.

"I see these findings less as a rejection of the amyloid theory and more as a possible link between amyloid beta and tau," he said.