New blood test developed to detect signs of Alzheimer’s disease

Scientists have developed a new test to detect signs of Alzheimer’s disease based on markers in a blood sample, an advance that may lead to better risk prediction for the neurological condition.

Currently, diagnosing Alzheimer’s disease requires “expensive” and time-consuming neuroimaging tests, say researchers, including those from the University of Pittsburgh in the US.

To diagnose the condition in patients, clinicians follow guidelines that require the detection of three distinct components of the condition’s pathology – the presence of amyloid plaques, tau tangles, and neurodegeneration in the brain.

Clinicians look for these signs of the disease either via neuroimaging or by analyzing cerebrospinal fluid (CSF) samples.

“A lot of patients, even in the US, don’t have access to MRI and PET scanners. Accessibility is a major issue,” study senior author Thomas Karikari said in a statement.

In the new research, published on Tuesday in the journal Brain, scientists sought to develop a diagnostic tool using biomarkers in blood samples – which can be collected with minimally invasive methods compared to CSF.

The most important utility of blood biomarkers is to make people’s lives better and to improve clinical confidence and risk prediction in Alzheimer’s disease diagnosis,” Dr Karikari said.

While current blood diagnostic methods can accurately detect abnormalities in plasma amyloid plaques and some forms of tau, researchers say the biggest hurdle lies in the difficulty of detecting markers specific to the brain and aren’t influenced by potentially misleading contaminants produced elsewhere in the body.

Citing an example, they say blood levels of neurofilament light – a protein marker of nerve cell damage – become elevated not only in Alzheimer’s disease, but also Parkinson’s and other dementias, causing its detection to be less useful when trying to differentiate Alzheimer’s from other neurodegenerative conditions.

In the latest study, researchers developed a new technique to selectively detect brain derived (BD)-tau while avoiding free-floating “big tau” proteins produced by cells outside the brain.

To achieve this, they designed a special antibody that selectively binds to BD-tau, making it easily detectable in the blood.

The levels of BD-tau detected in blood samples of Alzheimer’s disease patients in the study matched with levels of tau in the CSF and “reliably distinguished” Alzheimer’s from other neurodegenerative diseases, scientists say.

“A blood test is cheaper, safer and easier to administer, and it can improve clinical confidence in diagnosing Alzheimer’s and selecting participants for clinical trial and disease monitoring,” Dr Karikari said.

In further studies, scientists plan to conduct large-scale clinical validation of blood BD-tau in a wide range of research groups, including those that recruit participants from diverse racial and ethnic backgrounds.

Researchers also hope to test the method in those suffering from different stages of memory loss in future studies.