The trajectory of amyloid plaque buildup—clumps of abnormal proteins in the brain linked to Alzheimer’s disease—may serve as a more powerful biomarker for early detection of cognitive decline rather than using the total amount to gauge risk, researchers from Penn Medicine’s Department of Radiology suggest in a new study published online July 15 in the Journal of Neurobiology of Aging.

Amyloid plaque that starts to accumulate relatively early in the temporal lobe, compared to other areas and in particular to the frontal lobe, was associated with cognitively declining participants, the study found. “Knowing that certain brain abnormality patterns are associated with cognitive performance could have pivotal importance for the early detection and management of Alzheimer’s,” said senior author  Christos Davatzikos, PhD, professor in the Department of Radiology, the Center for Biomedical Image Computing and Analytics, at the Perelman School of Medicine at the University of Pennsylvania.

Today, memory decline and Alzheimer’s—which 5.4 million Americans live with today—is often assessed with a variety of tools, including physical and bio fluid tests and neuroimaging of total amyloid plaque in the brain.  Past studies have linked higher amounts of the plaque in dementia-free people with greater risk for developing the disorder. However, it’s more recently been shown that nearly a third of people with plaque on their brains never showed signs of cognitive decline, raising questions about its specific role in the disease.

Now, Dr. Davatzikos and his Penn colleagues, in collaboration with a team led by Susan M. Resnick, PhD, Chief, Laboratory of Behavioral Neuroscience at the National Institute on Aging (NIA), used Pittsburgh compound B (PiB) brain scans from the Baltimore Longitudinal Study of Aging’s Imaging Study and discovered a stronger association between memory decline and spatial patterns of amyloid plaque progression than the total amyloid burden.

“It appears to be more about the spatial pattern of this plaque progression, and not so much about the total amount found in brains. We saw a difference in the spatial distribution of plaques among cognitive declining and stable patients whose cognitive function had been measured over a 12-year period.  They had similar amounts of amyloid plaque, just in different spots,” Dr. Davatzikos said. “This is important because it potentially answers questions about the variability seen in clinical research among patients presenting plaque. It accumulates in different spatial patterns for different patients, and it’s that pattern growth that may determine whether your memory declines.”

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