By examining more than 3,600 postmortem brains, researchers at Mayo Clinic's campuses in Jacksonville, Florida, and Rochester, Minnesota, have found that the progression of dysfunctional tau protein drives the cognitive decline and memory loss seen in Alzheimer's disease. Amyloid, the other toxic protein that characterizes Alzheimer's, builds up as dementia progresses, but is not the primary culprit, they say.

The findings, published in Brain, offer new and valuable information in the long and ongoing debate about the relative contribution of amyloid and tau to the development and progression of cognitive dysfunction in Alzheimer's, says the study's lead author, Melissa E. Murray, Ph.D., a neuroscientist at Mayo Clinic in Jacksonville, Florida.