Scientists have developed a simple blood test that may help diagnose Alzheimer's disease in people with memory issues, an advance that provides a less invasive and low-cost alternative for brain imaging and spinal fluid tests.
The blood test, described in the journal Nature Medicine, detects the abnormal accumulation of a form of protein known as phosphorylated-tau-181 (ptau181), which is a biomarker that suggests brain changes due to Alzheimer's.
Over the past 15 years, research advances in the development of biomarkers like tau protein have enabled researchers to more accurately diagnose Alzheimer's disease, select research participants, and measure response to investigational therapies.
Tau and other biomarkers can be detected with PET scans of the brain and lab tests of spinal fluid, according to the researchers led by Adam Boxer at the University of California, San Francisco in the US.
However, PET imaging is expensive and involves radioactive agents, and spinal fluid tests require spinal taps, which are invasive, complex and time-consuming, they said.
"The considerable time and resources required for screening research participants with PET scans and spinal taps slow the pace of enrollment for Alzheimer's disease treatment studies," said Richard J Hodes, director of the National Institute on Aging (NIA) in the US.
"The development of a blood test would enable us to rapidly screen a much larger and more diverse group of volunteers who wish to enroll in studies," Hodes said.
Researchers used the new test to measure the concentration of ptau181 in plasma, which is the liquid part of blood that carries blood cells. The samples were collected from more than 400 participants.
Their analysis demonstrated that the ptau181 in plasma could differentiate healthy participants from those with Alzheimer's pathology.
It could also differentiate those with Alzheimer's pathology from a group of rare neurodegenerative diseases known collectively as frontotemporal lobar degeneration (FTLD).
"It has become clear that there are many possible biological pathways to dementia," said Roderick Corriveau, a programme director at US National Institute of Neurological Disorders and Stroke (NINDS).
"Finding a blood test that specifically identifies the presence of Alzheimer's pathology in the brain should greatly help researchers develop better treatments for the many who suffer from dementia," Corriveau said.
The results of the plasma ptau181 test mirrored results of two established biomarker tests for Alzheimer's -- a spinal fluid ptau181 test and a PET brain scan biomarker known as amyloid protein.
