April 9 (UPI) -- Researchers in Germany have developed a blood test for Alzheimer's that detects the disease several years before symptoms, including memory loss.
Ruhr University researchers hope the discovery leads to the development of new drugs by picking up pathological amyloid-beta in very early phases of the disease, which is incurable. Their findings were published Friday in EMBO Molecular Medicine.
"The use of the immuno‐infrared‐sensor as an initial screening funnel to identify people who should undergo further diagnostics and eventually take part in clinical trials on therapeutics targeting Aβ misfolding might already be an important step forward because subjects with early Alzheimer stages are hard to identify," the researchers wrote in the study. "To our knowledge, there is today no other plasma test available, which has been tested both in an Alzheimer's research cohort and in the general population."
Using the blood test, they found found those with Alzheimer's disease were 7.9 times more likely to test positive 15-20 years before clinical diagnosis.
The blood test is a much simpler process than the current, more expensive positron emission tomography, or PET, brain scans, or analysis of samples of cerebrospinal fluid that are extracted via lumbar puncture.
Klaus Gerwert, who led the team, developed a blood test that measures the ratio of pathological and healthy forms of amyloid in the blood. These amyloid-beta molecules start accumulating in patients' bodies 15 to 20 years before the disease's onset.
An immuno-infrared sensor measures distribution of pathological and healthy structures of amyloid-β. It's sticky, sheet-like folding pattern is prone to aggregation while healthy structure is not. They absorb infrared light at a different frequency.
Researchers first focused on patients in the early stages of the disease using the Swedish BioFinder cohort. The test reliably detected amyloid-beta alterations in the blood of participants with mild cognitive impairment that also showed abnormal amyloid deposits in brain scans.
Then they investigated whether the test could detect changes farther ahead of disease onset.
The researchers compared the blood samples of 65 participants that were later diagnosed with Alzheimer's disease with samples from 809 controls. Data was used from the Esther cohort study of older Caucasian adults conducted in the German state of Saarlan.
The test successfully detected the disease on average eight years before diagnosis in individuals without clinical symptoms.
The tested correctly identified almost 70 percent of the cases, while about 9 percent true negative subjects would wrongly be detected as positive. Overall, the diagnostic accuracy was 86 percent.
The researchers also hope to use the blood test to detect Parkinson's disease by measuring another disease biomarker, alpha-synuclein, instead of amyloid-beta.
A 2017 study by the University of Southern California found elevated levels of amyloid plaque in the brain are the first signs in the earliest stage of Alzheimer's.