New research finds that blood biomarkers associated with Alzheimer’s disease increase significantly faster in people with obesity than in those without. Drawing on five years of data from 407 volunteers, the study suggests that blood tests can detect obesity‑related changes earlier than brain scans, underscoring obesity as a major modifiable risk factor for Alzheimer’s.
Researchers at Washington University School of Medicine in St. Louis have conducted what they describe as the first study specifically evaluating how obesity affects Alzheimer’s disease blood biomarkers, or BBMs. The work, presented at the annual meeting of the Radiological Society of North America (RSNA) and detailed in materials from RSNA and ScienceDaily, analyzed long‑term data from participants in the Alzheimer’s Disease Neuroimaging Initiative.
Over roughly five years, the team drew on data from 407 volunteers, including amyloid positron emission tomography (PET) scans to measure beta‑amyloid plaque buildup in the brain and plasma samples that were tested for several Alzheimer’s‑related BBMs. According to the RSNA release and related coverage, these biomarkers included phosphorylated tau 217 (pTau217), neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP). Six leading commercial assays were used to analyze the blood samples.
At the start of the study, higher body mass index (BMI) was associated with lower levels of several blood biomarkers and a lower overall amyloid burden on PET. Lead author Soheil Mohammadi, M.D., M.P.H., a postdoctoral research associate at the Mallinckrodt Institute of Radiology, said in RSNA materials, “We believe the reduced BBMs in obese individuals was due to dilution from the higher blood volume.” He added that relying only on baseline measurements could give the misleading impression that people with obesity have less Alzheimer’s pathology.
Longitudinal analyses told a different story. Compared with participants without obesity, those with obesity showed substantially faster increases in multiple markers of Alzheimer’s‑related pathology over time. According to the RSNA and ScienceDaily summaries, people with obesity experienced a 29% to 95% faster increase in plasma pTau217 ratio levels, a 24% faster rise in plasma NfL and a 3.7% faster rate of amyloid accumulation on PET scans. Both blood biomarkers and brain imaging indicated greater buildup of Alzheimer’s‑related pathology in participants with obesity over the follow‑up period.
Senior author Cyrus Raji, M.D., Ph.D., a principal investigator in the Neuroimaging Labs Research Center at Washington University, emphasized that the blood tests were more sensitive than PET scans for picking up the influence of obesity on these changes. “The fact that we can track the predictive influence of obesity on rising blood biomarkers more sensitively than PET is what astonished me in this study,” he said in statements released by RSNA and reported in multiple news accounts.
The findings add to evidence that obesity is an important modifiable risk factor for Alzheimer’s disease. Mohammadi noted that, according to the 2024 report of the Lancet Commission, 14 modifiable risk factors together account for approximately 45%—close to half—of the overall risk for Alzheimer’s. “If we can reduce any of those risk factors, we can significantly reduce Alzheimer’s cases or lengthen the amount of time until the onset of the disease,” he said.
Looking ahead, Raji said he expects repeated measurements of blood biomarkers, combined with brain imaging, to become an increasingly common way to monitor how treatments affect brain health, including anti‑amyloid drugs and therapies targeting obesity. He suggested that having sensitive blood tests and MRI and PET imaging could allow clinicians and researchers to track both molecular pathology and structural brain changes over time. RSNA materials list Farzaneh Rahmani, M.D., M.P.H., Mahsa Dolatshahi, M.D., M.P.H., and Suzanne E. Schindler, M.D., Ph.D., as co‑authors on the study.
Note: While the biomarker and imaging findings are supported by conference materials, press releases and a related peer‑reviewed article on obesity and Alzheimer’s blood biomarkers, the work presented at RSNA has not yet been fully vetted through peer review in its conference form and should be interpreted accordingly.
