Subtle patterns of brain activity may reveal the risk of Alzheimer's disease years before memory problems develop or harmful proteins begin accumulating in the brain, according to new research led by Stanford Medicine. The same approach can also identify people whose brains show exceptional resistance to cognitive decline, suggesting they may eventually become "super agers."

The study, published November 4 in Science Advances, points to a potentially powerful new way to detect early warning signs of cognitive decline. Unlike conventional biomarkers, these patterns of brain activity might eventually be possible to change through targeted interventions.

To investigate, the research team examined brain activity in adults aged 75 and older who represented opposite ends of the cognitive aging spectrum. One group had Alzheimer's disease, while the other consisted of super agers, older individuals whose memories remained comparable to those of people decades younger.

Using the differences between these groups, the scientists created a scoring system to evaluate brain activity in cognitively healthy adults between 55 and 70.

The results revealed a striking connection between brain activity and future cognitive health. People whose brain patterns more closely resembled those of Alzheimer's patients were more likely to experience cognitive decline, accumulate amyloid-beta plaques, and receive an Alzheimer's diagnosis during follow-up periods extending up to 12 years.

Those with activity patterns resembling super agers were more likely to maintain their cognitive abilities and avoid these outcomes.

A New Way to Detect Alzheimer's Before Memory Loss

The new scoring system predicted future cognitive decline more effectively than several established indicators, including demographic characteristics, genetic risk factors, and amyloid-beta and tau biomarkers. This suggests that examining how different regions of the brain communicate could reveal Alzheimer's risk earlier than existing approaches.

"We want to address a major challenge in the Alzheimer's field nowadays -- most studies are looking at well-known Alzheimer's disease biomarkers, such as amyloid-beta or tau. But those are observable at relatively late stages of the disease," said Yu Zhang, PhD, assistant professor of psychiatry and behavioral sciences and senior author of the study.

"What we really care about is defining early markers that can detect earlier signs of cognitive decline and potentially help us deliver timely interventions to people."

Zhang envisions a future in which treatments could potentially move someone's brain activity toward the patterns associated with greater cognitive resilience. Possible approaches include cognitive training and transcranial magnetic stimulation, which uses magnetic pulses to influence brain activity.

Transcranial magnetic stimulation has already demonstrated potential for changing brain activity in people being treated for depression. However, neither of these proposed approaches has been tested in this context for preventing cognitive decline, and researchers do not yet know whether changing brain activity would alter the course of Alzheimer's disease.

The new findings provide a starting point for identifying which brain regions might be useful treatment targets.

"There are two main components: One is to know which part of the brain to target, the other is how we should change it," Zhang said. "That's why identifying the super-ager brain resilience pattern is a critical component -- so we know what a good pattern should be."

What Makes Super Agers' Brains Different?

Depending on how they are defined, approximately 10% of older adults may qualify as super agers. For this research, the term referred to people at least 75 years old who performed on memory tests at a level typical of a 45-year-old while maintaining normal executive function for their age.

Scientists have become increasingly interested in these unusually resilient individuals. Most earlier studies, however, compared super-agers with other older adults who performed normally on cognitive assessments.

Zhang recognized that this approach could overlook important biological differences. Two people might receive similar scores on memory tests despite having very different underlying brain health. One might already be developing amyloid-beta plaques or showing other biological changes associated with aging, while the other might not.

"Normal, cognitively unimpaired individuals are pretty heterogeneous in terms of their biological abnormalities," he said. "Simply comparing super agers with such a heterogeneous population makes it challenging to define what is critical in terms of resilient or vulnerable brain patterns."

In other words, comparing super agers with a broad mixture of seemingly healthy older adults makes it difficult to determine which brain characteristics actually protect against decline.

The Stanford team took a different approach. Rather than using typical older adults as the comparison group, they examined people with Alzheimer's disease who were approximately the same age as the super agers. This created two more clearly defined groups at opposite ends of the cognitive spectrum.

The researchers drew on imaging information collected through several major research initiatives, including the Open Access Series of Imaging Studies, the Harvard Aging Brain Study, and the Alzheimer's Disease Neuroimaging Initiative.

They…