Breakthrough blood test could detect early stages of Alzheimer’s YEARS before symptoms show

A NEW blood test could detect Alzheimer’s disease in its early stages, years before symptoms begin to show.

Tests that evaluate specific molecules in the blood could pick up early signs of Alzheimer’s-related brain decline, while being less invasive and more cost effective than current methods, scientists say.

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Alzheimer’s is usually diagnosed through physical examinations, memory tests and brain scans, as there currently isn’t a simple test to pick up the disease.

Detecting the brain robbing illness early enough for treatments to be effective has been a huge focus of recent research.

“Because the deterioration of cognitive functions in Alzheimer’s disease develops slowly over time, patients are currently diagnosed at an advanced stage of neuropathologic changes,” researchers from the Boston University Chobanian & Avedisian School of Medicine said.

“Indeed, the failure to diagnose Alzheimer’s at an early stage of molecular pathology is considered the major reason why multiple treatments have failed in clinical trials.”

Recent studies have yielded innovative ways of diagnosing Alzheimer’s, with scientists claiming that a blood test which can detect the disease up to 15 years before symptoms emerge could be made free on the NHS within a year.

The test works by measuring levels of a protein in the blood called p-tau217.

It fits into a form of molecular diagnosis that looks for what Boston University researchers referred to as “A/T/N” biomarkers.

This involves measuring levels of key proteins in the blood that are characteristic of Alzheimer’s – called beta-amyloid (“A”) and tau (“T”) – as well as looking at levels of neurodegeneration (“N”) in the brain.

But the research team claimed that measuring molecules in the blood called plasma microRNAs (miRNAs) may be more effective at picking up early signs of Alzheimer’s.

Alzheimer’s disease is thought to be triggered by genetics, as well as environmental risk factors and miRNAs control the expression of genes governing brain functions that deteriorate when someone has the brain robbing disease.

Scientists said that evaluating miRNAs in blood can be used to diagnose mild cognitive impairment (MCI), when someone has initial problems with memory and thinking.

For some people, MCI is an early sign of a disease that will eventually cause dementia.

Boston University researchers claimed that an miRNA blood test may also be able to predict if MCI might eventually turn into dementia, due to Alzheimer’s disease.

Their findings were published in two papers in the journal Alzheimer’s and Dementia.

Senior author Prof Ivana Delalle, of Boston University, said: “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.”

The researchers examined blood samples from 803 participants across 60 medical centres in the US and Canada.

They examined miRNA expression in blood plasma samples of three groups of participants – people who were “cognitively normal”, “mildly cognitively impaired” and patients with Alzheimer’s disease patients.

Using miRNA tests in combination with neuropsychological tests, researchers were able to predict whether participants with mild cognitive decline would later develop Alzheimer’s.

“Out of the 300 miRNAs reliably detected in plasma samples across individuals, we identified 15 miRNAs that were associated with Alzheimer’s disease, or helped detect early MCI and late MCI patients, or predicted their conversion to Alzheimer’s disease,” they explained.

Prof Andrew Saykin, of the IU School of Medicine who was also involved in the research, said: “These findings provide a path toward a better understanding the molecular mechanisms driving plaques, tangles and atrophy, and may provide clues for the next generation of therapeutic targets.”

While a number of new treatments for Alzheimer’s disease are being developed and rolled out, researchers said they can only work in a real-world setting if patients at risk are identified as early as possible.

This is where miRNA tests come in.

“We have laid the groundwork for further investigations into the role of microRNAs in Alzheimer’s disease pathogenesis,” study author Prof Kwangsik Nho, of the IU School of Medicine, said.

But more work needs to “refine and confirm” specific miRNA signatures that are associated with Alzheimer’s, researchers noted.

“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,” Prof Nho said.

Researchers concluded: “Integrating plasma microRNA signatures with established cognitive screening measures in primary care settings will likely enhance the accuracy and efficiency of recognising early Alzheimer’s-associated cognitive decline.”