Researchers have conducted the first study to examine how obesity affects Alzheimer’s disease blood biomarkers (BBMs). The findings, presented at the Radiological Society of North America (RSNA) annual meeting, showed that BBM levels rose up to 95% faster in people with obesity than in those without.
“This is the first time we’ve demonstrated a link between obesity and Alzheimer’s disease using blood biomarker tests,” said senior author Cyrus Raji, M.D., Ph.D., a principal investigator at the Neuroimaging Labs Research Center at Washington University School of Medicine’s Mallinckrodt Institute of Radiology.
Long-Term Imaging and Blood Analysis
The team analyzed five years of data from 407 volunteers participating in the Alzheimer’s Disease Neuroimaging Initiative. These participants underwent both amyloid PET scans—which reveal beta-amyloid plaque buildup—and routine blood draws.
Researchers measured several Alzheimer’s-related BBMs using six commercial tests, including pTau217, neurofilament light chain (NfL), and plasma GFAP, proteins associated with neuronal damage and astrocyte activity.
Connecting Body Weight and Brain Pathology
Using statistical modeling, the team examined how BBMs related to body mass index (BMI) and assessed interactions between obesity, time, and biomarker changes. They also validated the results against amyloid PET scans.
At the start of the study, higher BMI was linked to lower BBM levels and a lower amyloid burden. Lead author Soheil Mohammadi, M.D., M.P.H., explained that this likely reflected dilution due to higher blood volume in individuals with obesity.
“Baseline measurements alone could misleadingly suggest that people with obesity have less Alzheimer’s pathology,” he said. “Long-term data are necessary to understand how obesity shapes disease progression.”
Faster Alzheimer’s-Related Changes in Obesity
Over time, both BBMs and PET imaging showed a faster buildup of Alzheimer’s-related pathology in people with obesity. Participants with obesity had a 29% to 95% faster rise in plasma pTau217, a 24% faster increase in NfL, and a 3.7% faster rate of amyloid accumulation.
Dr. Raji noted that blood biomarkers detected obesity’s influence on Alzheimer’s progression more sensitively than PET scans. “The ability of blood tests to capture these changes so clearly was surprising,” he said.
Implications for Risk Reduction
Dr. Mohammadi emphasized that obesity’s effect on amyloid buildup and biomarker changes has major clinical implications.
“The Lancet Commission estimates that 14 modifiable risk factors account for nearly half of all Alzheimer’s risk,” he said. “Reducing any one of these factors could help delay or prevent disease onset.”
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