Novel blood test detects early signs of Alzheimer's

Raising hopes for an effective intervention in diagnosing the risk of early onset of disease, German scientists have developed a new blood test that can detect Alzheimer's long before the first symptoms appear in patients.

Alzheimer's disease is thought to begin long before patients show typical symptoms like memory loss.

The team, led by Klaus Gerwert, professor at Ruhr University Bochum in Germany, noted that one of the hallmarks of Alzheimer's disease is the accumulation of amyloid-beta plaques in the patient's brain.

The findings, published in the journal EMBO Molecular Medicine, showed that the blood test uses a technology called immuno-infrared sensor to measure distribution of pathological and healthy structures of amyloid-beta in the blood.

The pathological amyloid-beta structure is rich in a sticky, sheet-like folding pattern that makes it prone to aggregation, while the healthy structure is not.

The two structures absorb infrared light at a different frequency, allowing the blood test to determine the ratio of healthy to pathological amyloid-beta in the sample.

The pathological form is a misfolded version of this molecule and known to initiate the formation of toxic amyloid-beta molecules that starts accumulating in the brain 15 to 20 years before disease onset.

They found that 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.

In order to detect blood changes well ahead of disease onset, the researchers compared blood samples of 65 participants that were later in the follow-up studies diagnosed with Alzheimer's disease with 809 controls.

The assay was able to detect signs of the disease on average eight years before diagnosis in individuals without clinical symptoms with an overall diagnostic accuracy of 86 per cent.

The blood test would thus offer an opportunity to identify those at risk and may thereby open the door to new avenues in drug discovery, the researchers said.

--IANS

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