As researchers are still working on a cure for Alzheimer’s, early diagnosis remains a critical step in treatment and disease progression. To that end, researchers from the Florida International University are tackling the disease from an innovative diagnostic standpoint. They proposed a new portable biosensor that will diagnose Alzheimer’s progression by measuring beta-amyloid protein levels in the blood. The new test, researchers hope, could be done more cheaply and rapidly than current technologies, and so will enable personalized care to more Alzheimer’s patients, even in developing countries.
Alzheimer’s disease affects a staggering 44 million people worldwide. This number might actually be even greater, as some people with the condition go undetected.
Currently, diagnosing Alzheimer’s disease is limited and time-consuming. Doctors and experts have to conduct a battery of cognitive tests to look for impairments in cognition, memory, social functioning, and behaviors. These tests are highly subjective, but can be supported with neuroimaging data, such as magnetic resonance imaging (MRI) and positron emission tomography (PET) scans. Unfortunately, these methods are expensive and have limited accuracy. True Alzheimer’s diagnoses are confirmed when post-mortem autopsies reveal presence of beta-amyloid plaques and neurofibrillary tangles – neurological hallmark features of the disease.
In living patients, levels of beta-amyloid protein in the brain can be detected with enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) assays. However, these tests are complicated to perform and have low detection limits. The new proposed test circumvents these challenges by measuring the beta-amyloid biomarker from blood samples, using antibodies specific to the beta-amyloid protein.
In the blood-based biosensor assay, simplicity is key to its advantages. First, by using antibodies, the detection time can be cut by nearly 10-fold, taking 30-40 minutes compared to the 6 – 8 hours required by traditional ELISA tests. Second, because there is no complicated equipment attached, the assay can be run quickly, cheaply, and effectively. This moves the assay in the realm of point-of-care (POC) testing, giving patients and doctors nearly immediate results.
"We want to develop a point of care system, where a small drop of blood plasma can reveal their beta-amyloid level immediately so that a doctor can tailor a patient's therapy immediately," said Ajeet Kaushik, lead study author. "The drugs used to treat Alzheimer's disease can have side effects, so it's better for patients not to overdose. With the right data, doctors can respond quickly to changes in a patient's brain by reducing or increasing their dose."
And finally, the portability and simplicity of this test could translate to widespread use, even in underdeveloped areas. "Even though existing technologies are well established, we need to move towards small sample, high accuracy tests that can be used in all environments, from developed countries to rural settings. Our goal is to develop a test that's sensitive, small and affordable," said Kaushik.
This is the long-term goal, and the researchers have many tasks ahead to develop this biosensor. An important task will be collecting and measuring beta-amyloid levels at different stages of the disease, to create a standard to which other samples can be compared. While challenging, Kaushik is optimistic that “a rapid biosensor test for Alzheimer's disease will help scientists study disease progression and help clinicians deliver personalized therapy to patients."
Additional sources: EurekAlert!
, Biosensors and Bioelectronics