Serial PET Nails It: Preclinical AD Means Amyloid, Tau, then Cognitive Decline

08 Jun 2019

Amyloid deposits without causing symptoms for years, but once tau tangles accumulate, cognition craters. That’s the prevailing model for the progression of Alzheimer’s disease. The newest support for it comes from the first longitudinal study to repeatedly scan older adults for both amyloid and tau over years, and correlate the PET results with cognitive changes. In the June 3 JAMA Neurology, investigators in the lab of Keith Johnson at Massachusetts General Hospital in Boston reported that the rate of change of amyloid and tau was key—people who accumulated amyloid fastest experienced the most rapid ramp-up of tau, which in turn drove the biggest declines in cognition. Researchers saw it as an affirmation of a wealth of evidence gathered mostly from cross-sectional and pathological studies. “While it is not exactly surprising, it is exciting to see it demonstrated that it is not just cross-sectional amyloid or tau levels that are most closely linked to cognitive function … it is amyloid and tau changethat are most critical to final cognition seven years later,” wrote Samuel Lockhart, Wake Forest School of Medicine, Winston-Salem, North Carolina, to Alzforum (see comment below).