A team of researchers in Japan and Australia have developed blood test for Alzheimer’s disease that was able to accurately identify biomarkers of the disease in 90% of patients.
An estimated 5.5 million Americans in the United States are believed to have Alzheimer’s disease, the majority of which (5.3 million) are aged over 65. Approximately 200,000 individuals suffer from early onset Alzheimer’s disease. One in 10 Americans over the age of 65 years has Alzheimer’s related dementia.
There is currently no cure for Alzheimer’s disease, although treatments have been developed that can reduce the symptoms and slow the progression of the disease. The key to effective treatment is early diagnosis.
Alzheimer’s disease starts many years before the there are any noticeable symptoms, so typically, it is only when patients experience memory loss that they seek treatment and the disease is diagnosed. While the exact cause of the disease is not well understood, patients suffering from the disease have a build up of the toxic protein amyloid-β in the brain which is believed to cause brain cell death. Amyloid-β deposition in the brain is the earliest signature of the disease.
Currently, Alzheimer’s disease is diagnosed via two methods: An amyloid-β positron-emission tomography (PET) imaging scan of the brain or by checking the level of the amyloid-β biomarker in cerebrospinal fluid. Both of these diagnostic methods are invasive and expensive, so the key to early diagnosis is to develop a cheap and simple test that could be performed routinely in doctor’s surgeries – such as a blood test. However, until now there has been limited research that has established a link between amyloid-β in the blood and in the brain and cerebrospinal fluid.
The researchers have made considerable progress in this area and have developed a blood test for Alzheimer’s disease that has had highly positive results in a recent trial and established that it is possible to accurately estimate amyloid-β levels in the cerebrospinal fluid and brain from levels of the biomarker in the blood.
The test was used in a trial conducted on healthy patients, those with memory loss, and individuals who had already been diagnosed with Alzheimer’s disease. The blood test was used to detect the presence of amyloid-beta proteins in the plasma. By assessing the ratios of the types of amyloid-β fragments in the plasma, the researchers could accurately predict the level of amyloid-β deposition in the brain. The effectiveness of the test was compared to diagnoses using PIB-PET. The blood test was shown to be 90% accurate.
While the blood test has produced promising results, it has yet to be determined how accurate the test will be at detecting the disease in its early stages. The blood test for Alzheimer’s disease will also be of limited use to patients, since there is no cure for the disease; however, it could be of tremendous benefit to researchers and help identify patients for clinical trials.
Details of the recent trial and the blood test are detailed in the paper – High performance plasma amyloid-β biomarkers for Alzheimer’s disease – which was recently published in Nature.