Brain Scans May Show Alzheimer's-Linked Changes Seven Years Before Plaques Appear

A new study suggests brain imaging could reveal Alzheimer's-linked changes more than seven years earlier than researchers had previously believed. The work was led by scientists in the Department of Psychology at the University of Oslo and published in Nature Neuroscience. The findings suggest that amyloid-PET, a brain scan that detects amyloid plaque buildup and is currently the gold standard for early Alzheimer's imaging, may not be sensitive enough to capture the disease's earliest brain changes.

To find these changes, researchers followed healthy individuals who underwent regular MRI brain scans for nearly 20 years. The long span of data let the team determine when plaques first became detectable and which participants eventually developed them, then compare brain-structure changes between the two groups. "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, a postdoctoral researcher at the University of Oslo's Center for Lifespan Changes in Brain and Cognition during the study.

"The most groundbreaking aspect of this study is that we found structural changes in the brain many years before the first signs of plaque buildup, which is considered the earliest sign of Alzheimer's disease," said Anders Martin Fjell, professor at the Department of Psychology and head of the Center for Lifespan Changes in Brain and Cognition. Fjell said there are two possible explanations: harmful processes that contribute to or result from plaque accumulation may already be active in the brain before plaques can be detected by scanning, or other biological processes may be causing the brain changes even before amyloid plaques begin to accumulate.

The second possibility could matter for future Alzheimer's treatments, Fjell said: if brain changes begin through mechanisms separate from amyloid plaque accumulation, researchers may need to keep developing drugs that target other biological processes. "We need more research on this," he said.