New biomarker identified for diagnosing asymptomatic Alzheimer's disease

The study has identified a new biomarker for Alzheimer's disease in asymptomatic stages of the disease. This molecule is miR-519a-3p, a microRNA directly linked to the expression of the cellular prion protein (PrPC), which is disrupted in people suffering from certain neurodegenerative diseases such as Alzheimer's disease.

The study, carried out by the molecular and cellular neurobiotechnology group of the Institute of Bioengineering of Catalonia (IBEC) and the University of Barcelona, was published in the journal Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease.

The search for stable and easily detectable biomarkers in biofluids, such as microRNAs, offers hope for detecting Alzheimer's disease in its early, asymptomatic stages. Early detection can greatly improve diagnosis and treatment of this disease, which affects more than 35 million people worldwide.

First link between miR-519a-3p and PrPC in Alzheimer's disease The expression of several miRNAs is known to be dysregulated in patients with Alzheimer's disease. However, this is the first time that this microRNA has been specifically linked to decreased cellular prion protein production as the disease progresses.

"Currently, tests for diagnosing Alzheimer's disease are usually performed after the onset of symptoms, when cognitive impairment is already present. We believe that the discovery of this microRNA may help establish additional criteria for more accurate diagnosis in the early stages of the disease," explains IBEC lead researcher José Antonio del Rio, professor at the Department of Biology and the Institute of Neurosciences at the University of Barcelona (UB) and co-leader of the study.

The study also compares the presence of the biomarker in samples from other neurodegenerative diseases.

"If our goal is to use miR-519a-3p as a biomarker to detect Alzheimer's dementia in hypothetically healthy individuals, we need to ensure that its levels are not altered in other neurodegenerative diseases. In our study, we compared the levels of this biomarker in samples from other tauopathies and Parkinson's disease, confirming that miR-519a-3p changes are specific to Alzheimer's disease," said IBEC Senior Scientist Rosalina Gavin, UB assistant professor and co-principal investigator of the study.

Dayaneta Jacome, a researcher on Del Rio's team and first author of the study, notes that the team is making progress. The next step is to validate miR-519a-3p as a biomarker in blood samples from different cohorts of patients to begin its use in the clinical diagnosis of Alzheimer's disease in peripheral samples.

The researchers are members of the Center for Networked Biomedical Research in Neurodegenerative Diseases, CIBERNED.

MicroRNAs: Genetic Silencers The amount of cellular prion protein changes throughout Alzheimer's disease: levels are higher in the early stages of the disease, and levels decrease as the disease progresses. Although the mechanism responsible for these changes is not known in detail, it has been observed that certain microRNAs bind to a specific region of the PRNP gene, which controls the expression of PrPC, reducing it.

For this reason, and based on comparisons of previous studies and computational analyzes in various genomic databases, the researchers chose miR-519a-3p microRNA for their study.