Blood test for improved Alzheimer's diagnosis

Researchers at Saar University are developing a blood test for the diagnosis of Alzheimer's disease

07/30/2013

Alzheimer's may be diagnosed clearly and quickly using a blood test in the future. Scientists at the Institute of Human Genetics at the Saar University have succeeded in detecting the neurodegenerative disease based on certain blood signatures. Although the test has yet to prove itself in clinical trials, there is hope for a significant improvement in Alzheimer's diagnostics.

„Alzheimer's is the most common form of dementia. In Germany there are about 1.4 million people affected. By 2050, it should be around three million“, reports the University of Saarland in a recent press release. So far, the evidence of the disease is difficult or even impossible. In Alzheimer's diagnosis „It is usually a complex undertaking involving expensive procedures such as computed tomography or psychological tests such as memory and thinking“, so the message of the university. An early diagnosis is therefore hardly possible, but would be urgently needed in the interests of patients, since so far no cure, but only a delay in the course of Alzheimer's disease is possible. The blood test developed by the research team led by Petra Leidinger, Christina Backes and Andreas Keller at the Saar University, could bring me a significant improvement here. Their results have the researchers in the trade magazine „Genome Biology“ released.

Biomarkers are used to diagnose Alzheimer's disease
In the course of their studies, the scientists looked for so-called biomarkers, which can serve as reliable indicators of Alzheimer's during a blood test. „Biomarkers are molecules that scientists and physicians use to diagnose diseases and predict the course of disease“, explain Leidinger, Backes and Keller. As such, the so-called microRNAs - small, occurring in the blood nucleic acids - are suitable. Petra Leidinger from the Institute of Human Genetics in Homburg an der Saar explained that the microRNAs „are of great interest to medicine because their composition gives a specific signature that can be attributed to a particular disease.“ To determine whether Alzheimer specific microRNAs occur in the blood, the scientists have „tested the blood samples of 100 Alzheimer's patients“, reports Andreas Keller from the Institute of Human Genetics, who also works for Siemens Healthcare as Director Technology Innovation.

Precision of the Alzheimer's blood test at more than 90 percent
The researchers' search for specific biomarkers that indicate Alzheimer's disease was quite successful. „Overall, we found a different composition for twelve microRNAs than for the healthy controls“, report Leidinger, Backes and Keller. According to the researchers, a test based on the biomarker showed a pleasingly high level of accuracy. The precision of the test was more than 90 percent, which is a very good result for a biomarker. However, you need it „further investigations until clinical application“, Cord Stähler, Chief Technology Officer of Siemens Healthcare, said in the press release of the University of Saarland.

Differentiation from other neurological diseases is sometimes difficult
a also other brain illnesses cause partially similar symptoms as Alzheimer's, the researchers examined in a further step, „whether there are differences in the microRNA signature between Alzheimer's and other neurological diseases. Although settled Alzheimer „clearly differentiate here from schizophrenia or depression“, but „in other neurodegenerative diseases, such as Parkinson's and mild cognitive impairment, the test results were less accurate“, explained Leidinger. Although slight deviations of the biomarker have been found, but the clear distinction between Alzheimer's and the neurodegenerative diseases, they are not enough according to the researchers so far. „But this could be improved by further refining the molecular signatures“, reports the University of Saarland.

Insights into the molecular mechanisms in Alzheimer's
According to the researchers, the current search for Alzheimer's biomarkers has also „further insights into the molecular mechanisms in Alzheimer's“ allowed. Thus, two of the "microRNAs" involved in processes that lead to the formation of protein deposits (so-called plaques) in the brain of Alzheimer's patients. The plaques are considered a characteristic feature of the disease. Scientists from the Neurological Clinic at the University Hospital Erlangen, the Department of Internal Medicine II at the University of Heidelberg, the Charité Berlin and the Scripps Research Institute in La Jollla, California, were also involved in the study. (Fp)