Researchers looked for markers of Alzheimer's disease in more than 11,000 NorwegiansCredit: Tek Image/Science Photo Library
Nearly one in ten people over the age of 70 have Alzheimer’s disease dementia, shows a first-of-its-kind study that paired blood-based markers and clinical assessments to study the disease in Norway1.
That prevalence is in line with previous estimates for some other white populations2. But there were also unexpected differences, including higher disease rates than anticipated in individuals older than 85.
“This is very important work from a beautiful Norwegian study,” says Nicolas Villain, a neurologist at Sorbonne University in Paris who was not involved in the research. The study, published today in Nature, shows that blood-based tools can improve epidemiological estimates of neurodegenerative disease.
Blood tests are now approved for Alzheimer’s: how accurate are they?
But exactly how to use these tests remains controversial, warns Jason Karlawish, a geriatrician and co-director of the Penn Memory Center in Philadelphia, Pennsylvania. Blood-based markers can be helpful for physicians treating people with dementia and for answering research questions, but they aren’t ready to be rolled out widely as health screening tools.
“It is the kind of test that, in the wrong hands, could cause a lot of harm,” says Karlawish, who was not involved in the study.
From blood to brain
To assess the prevalence of Alzheimer’s disease (AD), an international team of researchers turned to the Trøndelag Health (HUNT) study, a prospective health research study that started in 1984 and that has collected health data and biological samples from 250,000 Norwegians.
Using blood samples from 11,486 individuals in the study aged 58 and above, the team looked at levels of a protein called tau that has been phosphorylated at a specific site. Known as pTau217, this blood marker serves as a proxy for the build-up of amyloid plaque in the brain, a hallmark of AD. HUNT study participants over the age of 70 have undergone cognitive testing, enabling the researchers to compare pTau217 levels with the presence of dementia.
... continue reading