Scientists have developed a blood test for Alzheimer’s disease Alzheimer’s disease

Scientists have developed a blood test to diagnose Alzheimer’s disease without the need for expensive or painful brain imaging lumbar puncture, where a sample of cerebrospinal fluid (CSF) is taken from the lower back. If confirmed, the test could enable faster diagnosis of the disease, meaning therapies could be started earlier.

Alzheimer’s is the most common form of dementia, but diagnosis remains challenging – especially during the early stages of the disease.

Current guidelines recommend the detection of three different markers: abnormal accumulations of amyloid and tau proteins, as well as neurodegeneration – the slow and progressive loss of neuronal cells in certain regions of the brain. This can be done through a combination of brain imaging and CSF analysis. However, a lumbar puncture can be painful and people may experience headaches or back pain after the procedure, while brain imaging is expensive and takes a long time.

Professor Thomas Karikari from the University of Pittsburgh in Pennsylvania, USA, who was involved in the study, said: “Many patients, even in the US, do not have access to MRI and PET scanners. Affordability is a big problem.”

The development of a reliable blood test would be an important step forward. “The blood test is cheaper, safer and easier to administer, and can improve clinical confidence in diagnosing Alzheimer’s disease and selecting participants for clinical trials and monitoring the disease,” Karikari said.

Although current blood tests can accurately detect abnormalities in amyloid and tau proteins, detecting brain-specific markers of nerve cell damage has been more difficult. Karikari and his colleagues around the world focused on developing an antibody-based blood test that would detect a particular form of tau protein called brain-derived tau that is specific to Alzheimer’s disease.

They tested it on 600 patients at various stages of Alzheimer’s disease and found that protein levels correlate well with tau levels in CSF and can reliably distinguish Alzheimer’s disease from other neurodegenerative diseases. Protein levels also closely matched the weight of amyloid plaques and tau knots in the brain tissue of people who had died of Alzheimer’s disease. The research was published in the journal Brain.

The next step will be to validate the test on a wider range of patients, including those of different racial and ethnic backgrounds and those suffering from different stages of memory loss or other potential symptoms of dementia.

Karikari also hopes that monitoring blood levels of brain-derived tau could improve the design of clinical trials to treat Alzheimer’s disease.