In a new study, researchers found a new blood test demonstrated remarkable promise in discriminating between people with and without Alzheimer’s disease and in people at known genetic risk may be able to detect the disease as early as 20 years before the onset of cognitive impairment.
The research was conducted by a team at Lund University and elsewhere.
Alzheimer’s is a debilitating and incurable disease that affects an estimated 5.8 million Americans age 65 and older.
Without the discovery of successful prevention therapies, the number of U.S. cases is projected to reach nearly 14 million by 2050.
For many years, the diagnosis of Alzheimer’s has been based on the characterization of amyloid plaques and tau tangles in the brain, typically after a person dies.
An inexpensive and widely available blood test for the presence of plaques and tangles would have a profound impact on Alzheimer’s research and care.
According to the new study, measurements of phospho-tau217 (p-tau217), one of the tau proteins found in tangles, could provide a relatively sensitive and accurate indicator of both plaques and tangles–corresponding to the diagnosis of Alzheimer’s–in living people.
In the study, the team evaluated a new p-tau217 blood test in 1,402 cognitively impaired and unimpaired people from well-known studies in Arizona, Sweden, and Colombia.
In the Arizona (Banner Sun Health Research Institute) Brain Donation Cohort, the plasma p-tau217 assay discriminated between Arizona Brain donors with and without the subsequent neuropathological diagnosis of “intermediate or high likelihood Alzheimer’s” with 89% accuracy.
it distinguished between those with and without a diagnosis of “high likelihood Alzheimer’s” with 98% accuracy; and higher ptau217 measurements were correlated with higher brain tangle counts only in those persons who also had amyloid plaques.
In the Swedish BioFINDER Study, the assay discriminated between persons with the clinical diagnoses of Alzheimer’s and other neurodegenerative diseases with 96% accuracy.
It distinguished between those with and without an abnormal tau PET scan with 93% accuracy.
In the Colombia Cohort, the assay began to distinguish between mutation carriers and non-carriers 20 years before their estimated age at the onset of mild cognitive impairment.
In each of these analyses, p-tau217 (a major component of Alzheimer’s disease-related tau tangles) performed better than p-tau181 (another component of tau tangles and a blood test recently found to have promise in the diagnosis of Alzheimer’s) and several other studied blood tests.
The team says blood tests like p-tau217 have the potential to revolutionize Alzheimer’s research, treatment and prevention trials, and clinical care.
One author of the study is Oskar Hansson, MD, PhD, Professor of Clinical Memory Research at Lund University.
The study is published in JAMA.
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