Alzheimer’s risk could increase with a common condition that affects millions, study says

The first study to evaluate the link between Alzheimer’s disease and body weight found a significant association.

Researchers at Washington Medical University in St. Louis, Missouri, found that Alzheimer’s blood biomarkers increased 95% faster in people with obesity than in non-obese people.

The study, which was presented Tuesday at the annual meeting of the Radiological Society of North America (RSNA) in Chicago, investigated five years of data from 407 participants in the Alzheimer’s Disease Neuroimaging Initiative, including PET (medical imaging) scans and blood samples.

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Researchers evaluated the association between Alzheimer’s biomarkers and body mass index (BMI), according to a news release.

When participants were first measured, higher BMI was associated with lower blood biomarkers of Alzheimer’s due to blood dilution, as people with higher body weight typically have a larger blood volume.

But when researchers followed the same participants over a longer period, they found that those with obesity developed a greater burden of Alzheimer’s disease than those without obesity.

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By analyzing how Alzheimer’s biomarkers matched PET scan results, they observed a buildup of amyloid plaques in the brain, a central feature of the most common type of dementia.

In an interview with News Digital, the study’s authors discussed the impact of these findings.

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“Our study shows that over a five-year period, obesity is associated with a steady increase in Alzheimer’s-related pathology,” said lead author Dr. Soheil Mohammadi, a postdoctoral research associate at the Mallinckrodt Institute of Radiology, part of WashU Medicine.

“What surprised me was the sensitivity of blood biomarkers in detecting this relationship. They captured subtle changes even better than brain imaging.”

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The study’s senior author, Dr. Cyrus Raji, an associate professor of radiology and neurology at the University of Washington, noted that the progression of Alzheimer’s is “influenced by pathologies that occur generally in the body, such as obesity.”

“It is essential to preserve brain health while also optimizing the health of the body,” he said.

Recent clinical trials (EVOKE and EVOKE+) have explored whether GLP-1 drugs such as semaglutide (Ozempic) could slow cognitive decline in people already diagnosed with early Alzheimer’s disease.

“Although Evoke’s recent trials failed to show an effect of Ozempic for the treatment of Alzheimer’s dementia, our work should motivate future trials to determine whether this class of drugs can help prevent Alzheimer’s by treating obesity earlier in life,” Raji said. “Caregivers and physicians are key partners in making these trials happen.”

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One limitation of this research, according to Mohammadi, is the fact that not all body fat carries the risk of Alzheimer’s disease.

“Our previous work shows that abdominal fat, rather than fat under the skin, drives much of the impact of obesity on the brain,” he said. “Future studies should distinguish between these types of fat rather than treating obesity as a single category.”

“Our previous work shows that abdominal fat, rather than fat under the skin, drives much of the impact of obesity on the brain.”

News senior medical analyst Dr. Marc Siegel, who was not involved in the research, said he considers it a “very important study.”

“I think this finding makes a lot of sense, because obesity directly leads to inflammation and insulin resistance, which causes neuroinflammation, one of the pillars of the development of Alzheimer’s,” he told News Digital.

The study had some limitations, the researchers noted.

The study sample was relatively small and specific, and may not represent the general population. Additionally, BMI measurement cannot distinguish between fat and muscle mass or reflect differences in fat distribution that may influence Alzheimer’s risk.

The study also relies on observational data, which can reveal associations but cannot prove that obesity directly causes faster Alzheimer’s pathology, the researchers noted.

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Other risk factors that often coincide with obesity, such as diabetes, hypertension and inflammation, may also contribute to changes in Alzheimer’s biomarkers.

This initial research raises the need to conduct larger studies in more diverse populations with longer follow-ups.