new research suggests.
Results from a large multinational study showed that the level of P-tau217 in blood collected during life was an accurate predictor of tau brain changes seen in brain tissue after death. In addition, increasing blood P-tau217 levels can be detected in some individuals up to 20 years before the average age of onset of the early cognitive decline that signals Alzheimer’s disease, researchers reported.
“While there is still more work to be done, this biomarker has the potential to have a transformational impact on research, treatment, prevention, and therapy development, and in the clinical setting,” said senior author Eric M. Reiman, MD, executive director of Banner Alzheimer’s Institute in Phoenix.
The findings were presented at the virtual annual meeting of the Alzheimer’s Association International Conference and simultaneously published online July 28 in JAMA.
Three cohorts
The international team of researchers evaluated the P-tau217 blood test in 1,402 adults from three cohorts. The first cohort was made up of 81 individuals in the Arizona (Banner Sun Health Research Institute) Brain Donation program and included clinical, blood, and neuropathologic data. The second cohort included 699 individuals in the Swedish BioFINDER-2 study and provided clinical, brain imaging, cerebrospinal fluid (CSF), and blood data. The third cohort was made up of 522 participants from the Columbian autosomal-dominant Alzheimer’s disease kindred, including 365 PSEN1 E280A mutation carriers and 257 mutation noncarriers.
In the Arizona cohort, plasma P-tau217 discriminated neuropathologically defined Alzheimer’s disease from non-Alzheimer’s disease (area under the curve, 0.89; 95% CI, 0.81-0.97) with significantly higher accuracy than plasma P-tau181 and neurofilament light chain (NfL) (AUC range, 0.50-0.72; P < .05).
In the Swedish BioFINDER-2 cohort, the discriminative accuracy of plasma P-tau217 for clinical Alzheimer’s disease dementia versus other neurodegenerative diseases was 96% (AUC, 0.96; 95% CI, 0.93-0.98).
This was significantly higher than plasma P-tau181, plasma NfL, and MRI measures (AUC range, 0.50-0.81; P < .001), but was not significantly different than CSF P-tau217, CSF P-tau181, and tau-PET (AUC range, 0.90-0.99; P > .15).
In the Colombian cohort, plasma P-tau217 levels were significantly greater among PSEN1 mutation carriers than noncarriers starting at around age 25 years, which is 20 years prior to the estimated onset of mild cognitive impairment among mutation carriers.
Additionally, plasma P-tau217 levels correlated with cerebral tau tangles, and discriminated abnormal versus normal tau-PET scans with significantly higher accuracy than plasma P-tau181, plasma NfL, CSF P-tau181, CSF Abeta42:Abeta40 ratio, and MRI measures.
The blood test “opens the possibility of early diagnosis of Alzheimer’s disease before the dementia stage, which is very important for clinical trials evaluating novel therapies that might stop or slow down the disease process,” presenting author Oskar Hansson, MD, PhD, of Lund (Sweden) University, said in a statement.
Further research is now needed to optimize the P-tau217 blood test, validate the findings in unselected and diverse populations, and determine its potential role in the clinic, the investigators noted.