Obesity may speed up Alzheimer’s progression, with blood tests detecting early effects more sensitively than PET brain scans, new research suggests.
The analysis tracked 407 people over five years, using blood samples and PET scans to spot signs of the disease.
PET (positron emission tomography) measures amyloid plaques, sticky protein clumps in the brain, while blood tests detect proteins linked to nerve damage and cognitive decline.
Over time, Alzheimer’s pathology progressed more quickly in people with obesity than in those without the condition, according to researchers at Washington University School of Medicine in St Louis.
The findings are not yet peer reviewed and were due to be presented on Tuesday at the Radiological Society of North America annual meeting.
Obesity was linked to a 24 per cent faster rise in plasma NfL, a protein indicating nerve fibre damage, and a 29 per cent to 95 per cent faster rise in plasma pTau217, a tau protein fragment tied to Alzheimer’s changes.
Amyloid plaque build-up was 3.7 per cent faster in people with obesity.
“This is the first time we’ve shown the relationship between obesity and Alzheimer’s as measured by blood biomarker tests,” said Dr Cyrus Raji, an associate professor of radiology and neurology at the university.
“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.”
Raji said the findings could help doctors monitor Alzheimer’s progression and assess the effectiveness of drugs designed to combat amyloid build-up.
“It’s marvellous that we have these blood biomarkers to track the molecular pathology of Alzheimer’s disease, and MRI scans to track additional evidence of brain degeneration and response to various treatments.”
Obesity is a known risk factor for Alzheimer’s.
People with obesity are also more likely to have high blood pressure, type 2 diabetes and lower physical activity levels, all of which contribute to dementia risk.
An estimated 57 million people worldwide have dementia, with Alzheimer’s causing 60 per cent to 70 per cent of cases, according to the World Health Organization.
