Stanford researchers developed an ARC score from resting brain scans that predicted faster cognitive decline in healthy adults over follow-up periods of up to 12 years.
Researchers at Stanford Medicine and colleagues have found that patterns of resting brain activity may predict who is more likely to develop memory problems years before symptoms appear.
The team compared two groups: 110 people with Alzheimer's disease and 180 adults at least 75 years old who scored better on memory tests than is typical for middle-aged adults. Researchers call this latter group SuperAgers.
Using functional MRI scans taken while participants lay still, the researchers looked for brain regions whose signals rose and fell together. Some connections involving the front of the brain were stronger in SuperAgers. Some involving the insula, a region tucked deep in the brain, were stronger in people with Alzheimer's.
"This suggests that Alzheimer's vulnerability may be reflected in how the brain functions as an interconnected system," Kanhao (Alex) Zhao, a postdoctoral researcher specializing in computational neuroscience at Stanford Medicine and the study's lead author, told ScienceAlert.
The team developed the Alzheimer's Resilience–Vulnerability Connectome, or ARC.
"The ARC score summarizes whether an individual's brain connectivity more closely resembles that of SuperAgers, who maintain exceptional memory into old age, or individuals with Alzheimer's disease," Zhao said.
Lower scores were more SuperAger-like and higher scores more Alzheimer's-like. When tested on a separate set of scans from 143 people who already belonged to one of those two groups, the method placed about 71 percent in the correct group.
The researchers then calculated ARC scores from the first scans of 1,315 adults with no cognitive impairment and compared them with test results and clinical assessments from later years. Most datasets covered about five to six years, and the longest extended to 12.
People with lower and higher ARC scores performed similarly on most tests at first. Over time, those with more Alzheimer's-like scans declined faster on assessments of memory and everyday functioning. They were also more likely to develop Alzheimer's disease or mild cognitive impairment.
Follow-up scans showed that amyloid beta, a protein that can build up into plaques in the brain, accumulated faster in people with more Alzheimer's-like scans, even though the groups started with similar levels. The researchers found no clear difference in the buildup of tau, another protein linked to Alzheimer's.
Adding ARC improved predictions of who would develop mild cognitive impairment or Alzheimer's beyond what researchers could predict using age, scans measuring amyloid beta and tau, and genetic risk linked to the APOE gene.
"We would need larger prospective studies following cognitively healthy individuals over several years, with validation across diverse populations and MRI scanners," Zhao said.
"These studies must establish reliable individual-level predictions, demonstrate added value beyond existing biomarkers, and determine whether ARC-informed assessments improve clinical decisions."
The research was published in Science Advances. If the findings hold up, the score could help researchers recruit people at higher risk into Alzheimer's prevention trials before memory problems begin. The researchers caution that ARC scores are not intended to diagnose Alzheimer's disease.
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This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.
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