Structural changes in the brain can be detected at least seven years before amyloid plaques become visible on PET scans, according to a study led by scientists in the Department of Psychology at the University of Oslo and published in Nature Neuroscience. That timeline pushes the earliest detectable signal of Alzheimer's-related change considerably further back than researchers had assumed.
Amyloid-PET imaging is currently treated as the gold standard for spotting the disease process at its earliest stages. The Oslo work suggests it may not be sensitive enough to catch everything that happens first, including changes tied to the processes behind plaque accumulation. In other words, by the time a PET scan lights up, the brain may already have been changing measurably for years.
"We found that structural changes in the brain occur many years before high levels of plaque are seen on PET scans, which is the brain scan currently used to identify the earliest signs of Alzheimer's disease," said James Michael Roe, who led the research as a postdoctoral researcher at the Center for Lifespan Changes in Brain and Cognition at the University of Oslo. He is now International Scientific Lead at Cercare Medical.
For patients and families, the practical significance lies in timing. Treatments aimed at amyloid work best the earlier they are given, so any imaging signal that arrives years ahead of a positive PET scan widens the window in which intervention or prevention trials could plausibly act. Whether these structural changes are specific enough to identify individuals who will go on to develop Alzheimer's, rather than simply reflecting ageing brains in general, is the question that follow-up work will have to answer.