Asst Prof Shao (far left) and her team invented APEX, a highly sensitive blood test for early detection of Alzheimer's disease, even before clinical symptoms appear
Asst Prof Shao (far left) and her team invented APEX, a highly sensitive blood test for early detection of Alzheimer's disease, even before clinical symptoms appear NUS website

National University of Singapore (NUS) researchers invented APEX (Amplified Plasmonic EXosome) system to diagnose and the most common cause of severe dementia, Alzheimer's disease (AD) and monitor a patient's response to treat the individual by doing a simple blood test.

NUS revealed that the key characteristic of AD is the buildup of amyloid beta (Aβ) proteins, which clump up as aggregates and kill brain cells and these are also released into and circulate through the bloodstream.

The APEX system is designed only to detect and analyse the earliest aggregated forms of Aβ proteins in blood samples, to detect AD even before clinical symptoms appear and to accurately classify the disease stages, said NUS in a news release.

A doctoral student from NUS iHealthtech and NUS Biomedical Engineering, Carine Lim, who is also the co-first author of the study stated that "Traditional technologies measure all Aβ molecules found in the blood, regardless of their aggregation states, and thus show poor correlation to brain pathology," but this new study has found that the aggregated form of the protein could accurately reveal brain changes and reflect the disease stage.

It should be noted that compared to the brain positron emission tomography (PET) imaging, the current gold standard for AD diagnosis costs around $30 per test, which is less than one percent of the cost of PET imaging.

The researchers mentioned that this design could test 60 samples simultaneously, with the results available in less than one hour. As the APEX system uses native blood plasma without additional sample processing, it conducts direct measurement and can be used in clinical settings.

To determine the performance of the APEX system, the lead author of the study Assistant Professor Shao Huilin from the NUS Institute for Health Innovation & Technology (NUS iHealthtech) along with her team conducted a clinical study involving 84 people, including patients who have been diagnosed with AD or mild cognitive impairment (MCI), as well as a control group comprising healthy individuals and patients diagnosed with vascular dementia or neurovascular compromises. PET imaging and blood sampling were also carried out on all individuals.

After the results came out, Prof Shao said that it showed the APEX system can successfully with full accuracy identified "patients with AD and those with MCI; it also differentiates them from healthy individuals and patients suffering from other neurodegenerative diseases."

"In fact, this is the only blood test that shows such comparable results with PET imaging, the current gold standard for AD diagnosis," she added.

The team of researchers are currently discussing with industry partners to commercialise this technology. Each APEX chip is 3 cm by 3 cm, which means it is about a quarter the size of a credit card and contains 60 neatly-arranged sensors.