Researchers from Japan and Australia have teamed up to develop and validate a blood test for Alzheimer’s disease, which has the potential to massively ramp up the pace of drug trials.
The blood test measures a specific peptide in the blood to inform scientists, with 90 per cent accuracy, if a patient has the very earliest stages of Alzheimer’s disease.
One of the essential hallmarks of Alzheimer’s disease is build up of abnormal peptide in the brain, known as beta-amyloid. The process starts silently about 30 years before outward signs of dementia, like memory loss or cognitive decline, begin to present.
Currently, levels of amyloid-beta in the brain can only be assessed reliably via brain imaging (PET scans) or by measuring amyloid-beta levels in the cerebrospinal fluid (lumbar puncture). For that reason, there is an urgent need for a more cost-effective and less-invasive diagnostic tool.
The research, a partnership between the Japanese National Center for Geriatrics and Gerontology (NCGG) and the Australian Imaging, Biomarker and Lifestyle Study of Aging (AIBL), involved measuring the levels of several amyloid-beta-associated biomarkers in the blood in cognitively normal individuals, people with mild cognitive impairment and those with Alzheimer’s disease, with a total of 373 participants involved.
Researchers found the ratios of the different amyloid-beta-associated biomarkers in the blood accurately predicted amyloid-beta deposition in an individual’s brain.
The blood test will help researchers recruit more people into clinical trials who are accurately identified as being ‘at-risk’ of Alzheimer’s disease. Clinical trials are expected to be most effective when patients are in the earliest stages of the disease, and the blood test may aid the selection of suitable clinical trial participants.
For consumers, it is a cost-effective and less-invasive diagnostic tool. Eventually, people who have the test will be able to find out if they have an increased likelihood of developing Alzheimer’s disease, decades before obvious symptoms emerge. This would give people the opportunity to seek treatment sooner, and make some lifestyle changes, such as adjustment to sleep, exercise and diet, to potentially delay the onset of the disease.
Professor Colin Masters of the Florey Institute of Neuroscience and Mental Health, who co-led the research, says this new test has the potential to eventually disrupt the expensive and invasive scanning and spinal fluid technologies.
“In the first instance, however, it will be an invaluable tool in increasing the speed of screening potential patients for new drug trials,” Professor Masters said.
“Progress in developing new therapeutic strategies for Alzheimer’s disease has been disappointingly slow. None of the three drugs currently on the market treat the underlying disease. New drugs are urgently required, and the only way to do that is to speed up whole process. That requires trials with rigorous and economical patient selection, to avoid recruiting patients who may not even have Alzheimer’s disease. Due to the long timespans involved, pharmaceutical companies require accurate predictions of who is most at risk.”
However, it must be noted that while the test tells the clinician that amyloid levels in the brain are elevated, there also needs to be memory loss to diagnose Alzheimer’s disease, so the blood test does not replace the use of cognitive assessments. Some people with elevated levels of amyloid-beta in the brain may never go on to develop Alzheimer’s disease.
Dr Vincent Doré, Research Scientist Biomedical Imaging at the CSIRO, whose software was used by researchers to carry out the validation, says there is still a way to go before the test is made available to the general public.
“Right now, the test isn’t very portable – it has to be run through a fully equipped, high-tech lab. A lot more work is needed before the test can be used widely, including longitudinal studies, optimisation of cut-off values as well as the mathematical generation of the composite biomarker,” Dr Doré said.
The test may be available to the public on a wider scale within about five years, at which point people aged 55 to 60 could visit their GP for a check-up and the blood test.
The research is available to view in full at the Nature website.