New Blood Test Shows Great Promise in Diagnosis of Alzheimer Disease

A new blood test has shown promise in differentiating individuals with and without Alzheimer disease. The test also may be able to detect the disease in those with a genetic risk as early as 20 years before the onset of cognitive impairment, according to a press release.

In the new study, published in the Journal of the American Medical Association, measurements of phosphor-tau217 (p-tau217) were found to provide a relatively sensitive and accurate indicator of both plaques and tangles corresponding to Alzheimer disease in living people.

“The p-tau217 blood test has great promise in the diagnosis, early detection, and study of Alzheimer’s,” said senior study author Oskar Hansson, MD, PhD, in a press release. “While more work is needed to optimize the assay and test it in other people before it becomes available in the clinic, the blood test might become especially useful to improve the recognition, diagnosis, and care of people in the primary care setting.”

The researchers evaluated a new p-tau217 blood test in 1402 cognitively impaired and unimpaired research participants from well-known studies in Arizona, Sweden, and Colombia.

The study included:

• 81 Arizona participants in Banner Sun Health Research Institute’s Brain Donation program who had clinical assessments and provided blood samples in their last years of life and then had neuropathological assessments after they died.
• 699 participants in the Swedish BioFINDER Study who had clinical, brain imaging, cerebrospinal fluid (CSF), and blood-based biomarker assessments.
• 522 Colombian autosomal dominant Alzheimer disease (ADAD)-causing mutation carriers and non-carriers from the world’s largest ADAD cohort.

In the Arizona study, the plasma p-tau217 assay categorized Arizona brain donors with and without the subsequent neuropathological diagnosis of intermediate or high likelihood Alzheimer with 89% accuracy. Further, it distinguished between those with and without a diagnosis of high likelihood of Alzheimer with 98% accuracy. The higher p-tau217 measurements were correlated with higher brain tangle counts only in those people who also had amyloid plaques.

In the Swedish study, the assay differentiated between people with the clinical diagnosis of Alzheimer and other neurodegenerative diseases with 96% accuracy, similar to tau PET scans and CSF biomarkers and better than other blood tests and MRI measurements, according to the press release. In addition, it distinguished between those with and without an abnormal tau PET scan with 93% accuracy.

The Colombia cohort found the assay began to distinguish between mutation carriers and non-carriers 20 years before their estimated age at the onset of mild cognitive impairment, according to the press release.

In each of these analyses, p-tau217 performed better than p-tau181, which is another component of tau tangles; a blood test recently found to have promise in the diagnosis of Alzheimer and several other studied blood tests.

Although more work is needed before the test is ready for clinical use, a p-tau217 blood test has the potential to provide information about both plaques and tangles, corresponding to the diagnosis of Alzheimer. It has the potential to advance the disease’s research and care in other important ways, according to the study authors.

“Blood tests like p-tau217 have the potential to revolutionize Alzheimer’s research, treatment and prevention trials, and clinical care,” said senior author Eric Reiman, MD, executive director of Banner Alzheimer’s Institute in Phoenix, in a press release. “While there’s more work to do, I anticipate that their impact in both the research and clinical setting will become readily apparent within the next two years.”

REFERENCE

New blood test shows great promise in the diagnosis of Alzheimer disease. Lund University. https://www.lunduniversity.lu.se/article/new-blood-test-shows-great-promise-diagnosis-alzheimers-disease. Published July 28, 2020. Accessed August 10, 2020.