Brain Changes May Precede Detectable Alzheimer’s Plaques by at Least 7 Years
A University of Oslo study found structural changes in the brains of healthy older adults at least seven years before amyloid plaques became detectable with PET scans. The findings, based on repeated imaging over nearly two decades, suggest that some disease-associated processes may begin before current scans reveal plaque buildup.
Structural changes associated with Alzheimer’s disease may appear at least seven years before amyloid plaques become detectable with current PET scans, according to a study led by researchers at the University of Oslo and published in Nature Neuroscience.
The researchers reached this conclusion by tracking healthy older adults who underwent repeated brain imaging over nearly 20 years. After identifying participants who eventually developed detectable amyloid plaques, the team reviewed MRI scans from the preceding decade and compared changes in brain structure with those seen in participants who did not develop visible plaques.
The study focused on cortical thickness, a measure of the brain’s outer layer. The researchers reported that changes in cortical thickness preceded the appearance of high amyloid levels on PET scans by at least seven years. The participants were cognitively well-functioning older individuals when the imaging data were collected.
Amyloid-PET is described in the report as the current imaging standard for identifying early signs of Alzheimer’s-related plaque accumulation. The findings suggest that the technique may not capture every structural change occurring during the earliest stages of the disease process.
James Michael Roe, the study’s main researcher while at the University of Oslo’s Center for Lifespan Changes in Brain and Cognition, said the structural signal could eventually help researchers track disease-related changes before symptoms emerge. Anders Martin Fjell, professor at the University of Oslo and head of the center, said the long-term imaging record was important because it allowed the researchers to examine brain changes before plaques were visible on scans.
The findings do not establish that the observed structural changes cause amyloid plaques, nor do they show that MRI can currently diagnose Alzheimer’s disease before symptoms or visible plaque buildup. Instead, they identify an earlier brain signal associated with the later appearance of detectable plaques in the studied group.
The researchers offered two possible explanations. Processes that contribute to plaque accumulation—or result from it—could already be active before plaques are detectable. Alternatively, other biological processes might be changing brain structure before amyloid plaques begin to accumulate. The study does not resolve which explanation is correct.
That distinction could matter for future treatment research. If some early structural changes arise through mechanisms separate from amyloid accumulation, the researchers said therapies targeting biological processes beyond plaques may warrant continued investigation. They also emphasized that more research is needed to understand the relationship between the early MRI changes, plaque development and later cognitive symptoms.
Reporting Note
Biohack Report distinguishes preliminary findings, clinical evidence and commercial claims whenever the available reporting supports that distinction. Coverage is informational and is not medical advice.