MRI Scans Might Reveal Signs of Alzheimer's Disease Seven Years Before a Telltale Marker Appears in the Brain

Alzheimer’s disease is a devastating neurodegenerative disorder and the most common form of dementia. It’s marked by the abnormal buildup of two proteins in the brain—tangles of tau and sticky plaques of beta-amyloid—that damage nerve cells. Physicians can currently use PET scans to search for amyloid plaques.

People already experiencing cognitive decline tend to seek them out to determine whether they have Alzheimer’s. Now, researchers say a different kind of brain imaging can help them see signs associated with the disease even sooner. Changes in the thickness of the cortex—the brain’s wrinkly outer layer—viewed via MRI scans seem to precede abnormal amyloid buildup and can be detected at least seven years before the protein is detected in PET scans.

The findings, published in the journal Nature Neuroscience on August 19, could help researchers better understand the beginnings of Alzheimer’s, which affects more than seven million Americans ages 65 and older. Roe and colleagues examined longitudinal data from more than 1,000 adults who did not have dementia when they enrolled in the research. Participants were followed for up to 16 years and had multiple MRI scans throughout that time.

Nearly 700 of them also had amyloid-PET scans. Together, the data allowed the researchers to look at differences in the brains of people who developed Alzheimer’s and those who didn’t, as well as compare what appeared in the two imaging techniques—and when. Analyses revealed an association between cortical thickness and people who developed amyloid plaques years later.

The wrinkly layer naturally thins with age, but it remained a bit thicker in people who eventually showed elevated amounts of beta-amyloid than those who did not. The changes seen via MRI were visible at least seven years before plaques could be viewed via PET scan. The findings suggest a potential for earlier interventions, says Lucy Hooper, a physician and co-founder of Coyne Medical, a London-based private clinic, who was not involved in the study, to Maria Azzurra Volpe at Newsweek.

However, the changes in cortical thickness are probably too subtle to use to diagnose the neurodegenerative disease, says Frederik Barkhof, a neuroradiologist at University College London who also wasn’t involved in the work, to Skyler Ware at Science News. Still, he thinks the results can help researchers understand the drivers of Alzheimer’s disease and emerging treatments. An experimental Alzheimer’s drug targeting tau Amyloid plaques have been a major target for Alzheimer’s drugs.