Blood test predicts Alzheimer's 16 years ahead

After years of research, a simple blood test has been developed that can predict familial Alzheimer's disease up to 16 years before clinical symptoms appear.

The blood test reliably detects signs of brain damage in people on the path to developing Alzheimer’s disease — even before they show signs of confusion and memory loss, according to a new study.

Neuroscience Research Australia (NeuRA), part of the Dominantly Inherited Alzheimer Network (DIAN), collaborated on a publication in Nature Medicine that details evidence for the blood test.

The DIAN study, which has been running since 2008, involves a global network of researchers, led by Professors John Morris and Randall Bateman at Washington University, St Louis, Missouri with study sites in the USA, England, Germany and three research teams in Australia — NeuRA, The Florey Institute and the Edith Cowen University in WA. Together, researchers have been working with the rare families who carry the inherited Alzheimer’s disease genes to identify the biomarkers for potential predictive testing in the future.

Professor Colin Masters AO from the Florey Institute said, “The blood test accurately predicted when members of a family with inherited Alzheimer’s disease would begin to show symptoms. Inherited Alzheimer’s is rare genetic disease. Using this very defined patient population we were able to identify affected family members over a decade before they began to show cognitive impairments.”

There is hope that the blood test will eventually be useful for a wider range of people who may be at risk of the common form of older-onset Alzheimer’s disease known as ‘sporadic’, as well as those with the genetic version.

Neurofilament light, or NfL, is a crucial building block of brain cells. When these cells start to die in Alzheimer’s disease, traumatic brain injury or other neurodegenerative diseases, this building block is released into the blood stream.

The data showed that when patients converted from pre-symptomatic disease to having clear cognitive and memory decline, NfL built up in the blood at the fastest rate.

“NfL levels rise whenever the brain is damaged, and as Alzheimer’s disease affects 30% of people over the age of 80, we hope that NfL will become part of a GP’s standard battery, like annual cholesterol testing. We would send patients off for more specific Alzheimer’s tests if the results come back showing a cause for concern,” Professor Masters said.

If a patient is identified as being in the early phase of the disease, they could be referred to a pharmacological clinical trial, make diet and lifestyle modifications and be placed on existing medications in the hope of slowing down disease progression.

Next steps for the test include replicating the results in sporadic Alzheimer’s disease patients, who are older and often have other health issues. The Australian Imaging Biomarker and Lifestyle (AIBL) patient samples will be used to validate these test results.

The study, Serum neurofilament dynamics predicts neurodegeneration and clinical progression in pre-symptomatic Alzheimer’s Disease, was published this month in Nature Medicine.

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