A commercially available blood test was trialled in healthcare settings.
ADVERTISEMENTBlood tests for Alzheimer's disease aim to help doctors diagnose the condition more quickly and accurately but are mostly used in controlled research settings.
A new Swedish study shows their reliability in real-world healthcare settings as well.
The study of more than 1,200 patients experiencing mild memory symptoms found that a blood test for Alzheimer's had 90 per cent reliability in primary care.
Alzheimer's can be cumbersome to diagnose, requiring a hard-to-get brain scan or an uncomfortable spinal tap. Many patients are diagnosed based on symptoms and cognitive exams.
In the Swedish study, patients who visited either a primary care doctor or a specialist for memory complaints got an initial diagnosis using traditional exams, gave blood for testing and were sent for a confirmatory spinal tap or brain scan.
Blood testing was far more accurate, Lund University researchers reported on Sunday at the Alzheimer's Association International Conference in Philadelphia.
The primary care doctors' initial diagnosis was 61 per cent accurate and the specialists' 73 per cent, but the blood test was 91 per cent accurate, according to the findings, which also were published in the Journal of the American Medical Association.
“The blood test can determine with 90 per cent accuracy whether a person experiencing memory loss is suffering from Alzheimer’s,” Sebastian Palmqvist, associate professor of neurology at Lund University and one of the study's co-lead authors, said in a statement.
Oskar Hansson, a professor of neurology at Lund University and the other lead author, added in a statement that "early diagnosis is crucial as new treatments that slow the disease’s progression are developed".
"The next steps include establishing clear clinical guidelines for the blood test’s use in healthcare," Hansson said.
Which blood tests for Alzheimer’s work best?
Labs have begun offering a variety of tests that can detect certain signs of Alzheimer's in blood.
Scientists are excited by their potential but the tests aren't widely used yet because there's little data to guide doctors about which kind to order and when.
“What tests can we trust?” asked Dr Suzanne Schindler, a neurologist at Washington University in St. Louis who’s part of a research project examining that.
While some are very accurate, “other tests are not much better than a flip of a coin".
There’s almost “a wild West” in the variety being offered, said Dr John Hsiao of the National Institute on Ageing. They measure different biomarkers, in different ways.
ADVERTISEMENTDoctors and researchers should only use blood tests proven to have a greater than 90 per cent accuracy rate, said Alzheimer’s Association chief science officer Maria Carrillo.
For now, Carrillo said doctors should use blood testing only in people with memory problems, after checking the accuracy of the type they order.
Alzheimer's disease is the most common form of dementia and is estimated to affect roughly 7.8 million Europeans. According to the organisation Alzheimer Europe, that number will almost double by 2050.
