New Alzheimer’S Studies Reveal Disease Biology, Risk For Progression, And The Potential For A Novel Blood Test

The failure to diagnose Alzheimer's disease, the most common form of dementia in the elderly, at an early stage of molecular pathology is considered a major reason why treatments fail in clinical trials. Previous research to molecularly diagnose Alzheimer's disease yielded "A/T/N" central biomarkers based on the measurements of proteins, β-amyloid ("A") and tau ("T"), and "N" encompassing neurodegeneration. A/T/N can be measured in brain tissue, by in vivo brain imaging techniques, and by analysis of cerebrospinal fluid and plasma.

Two new papers by a team of researchers at Boston University, the Indiana University School of Medicine and the Alzheimer's Disease Neuroimaging Initiative (ADNI), and the German Center for Neurodegenerative Diseases (DZNE) in Goettingen, Germany, published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association demonstrate that evaluating microRNAs in blood can be used not only to diagnose mild cognitive impairment (MCI) but also, critically, to predict the conversion from MCI to dementia due to Alzheimer's disease. Moreover, the researchers uncovered microRNA candidate molecular biomarkers that associate with current Amyloid, Tau, and Neurodegeneration (A/T/N) Alzheimer's biomarkers.

"Our papers are the result of a successful collaboration that tied the technology developed by professor Andre Fischer in Germany's DZNE to reliably measure the levels of microRNA in human plasma, and the power of blood samples obtained from hundreds of ADNI participants participating in a simulated clinical trial taking place at about 60 medical centers across the US and Canada. Our discovery is important because, unlike the current A/T/N biomarkers, microRNAs may serve as blood molecular biomarkers years before Alzheimer's disease manifests clinically, thus identifying the time window for effective prevention or early intervention to stop the progression of Alzheimer's," explained one of four senior authors Ivana Delalle, MD, PhD, professor of pathology & laboratory medicine at Boston University Chobanian & Avedisian School of Medicine.

The other senior authors are Andre Fischer, PhD, DZNE speaker and professor of epigenetics of neurodegenerative diseases at University Medical Center Goettingen, Germany; Kwangsik Nho, PhD, professor of radiology and imaging sciences at the IU School of Medicine; and Andrew J. Saykin, PsyD, Raymond C. Beeler Professor of Radiology and director of the Center for Neuroimaging and the Indiana Alzheimer's Disease Research Center at the IU School of Medicine. The work was funded by the National Institutes of Health's National Institute on Aging multisite project RF1AG078299. "MicroRNAs as Diagnostic and Prognostic Biomarker of Alzheimer's Disease" that supports the teams of researchers in multiple institutions.

The researchers examined miRNA expression in the plasma samples of three diagnostic groups of participants-;cognitively normal, mildly cognitively impaired and dementia due to Alzheimer's disease patients. They found that, when combined with neuropsychological testing, plasma microRNAome evaluation helps predict which aging individuals concerned about cognitive decline will progress to develop Alzheimer's.

While these are exciting times with novel therapies for Alzheimer's disease entering clinical care, the researchers note that those therapies only will work in a real-world setting if patients at risk are identified as early as possible.

"We have laid the groundwork for further investigations into the role of microRNAs in Alzheimer's disease pathogenesis," Nho said. "We envision that once specific miRNA signatures are further confirmed, the analysis of blood miRNAs will be transferred to simple assay formats enabling the adoption of blood miRNAome analysis in clinical practice."

The researchers said improved tools for the early detection of Alzheimer's are indispensable for developing prevention and treatment strategies for the disease that is causing enormous suffering and burdens health care systems around the world.

Source:

Indiana University

Journal references:

Krüger, D. M., et al. (2024). The plasma miRNAome in ADNI: Signatures to aid the detection of at‐risk individuals. Alzheimer’s & Dementia. doi.org/10.1002/alz.14157.