Plasma p-tau assay highly accurate in identifying Alzheimer’s-related pathology

Key Takeaways:

• Researchers analyzed data from 786 older adults from 3 Alzheimer’s-related groups.
• Accuracy of the assay was comparable with cerebrospinal fluid biomarkers in determining an abnormal PET signal.

A plasma phosphorylated-tau217 assay demonstrated a high degree of accuracy in identifying biomarkers consistent with Alzheimer’s disease-related pathology, according to research from JAMA Neurology.

“Blood biomarkers have emerged as scalable tools for clinical evaluation, trial recruitment and disease monitoring,” Nicholas J. Ashton, PhD, a researcher in the department of psychiatry and neurochemistry at the Institute of Neuroscience and Physiology at Sahlgrenska Academy in the University of Gothenburg, and colleagues wrote. “Phosphorylated tau is the leading blood biomarker candidate, demonstrating superior diagnostic accuracy and disease specificity compared with other candidates.

Ashton and colleagues aimed to determine the utility of an immunoassay for plasma p-tau217 to detect AD pathology and evaluate reference ranges for abnormal amyloid beta and longitudinal changes across multiple cohorts of older adults who may or may not show evidence of cognitive issues indicative of the condition.

Their study examined data from three single-center observational groups: cross-sectional and longitudinal data from the Translational Biomarkers in Aging and Dementia cohort, the Wisconsin Registry for Alzheimer’s Prevention cohort and cross-sectional data from the Sant Pau Initiative on Neurodegeneration cohort.

A total of 786 participants (mean age 66.3 years; 64.1% female) were included for analysis, including those with and without cognitive impairment grouped by amyloid and tau (AT) status measured via positron emission tomography (PET) or cerebrospinal fluid (CSF) biomarkers.

The main outcome was accuracy of plasma p-tau217 in detecting abnormal amyloid and tau pathology as well as longitudinal p-tau217 change according to baseline pathology status.

The researchers reported a high degree of accuracy in identifying elevated amyloid beta (area under the curve [AUC], 0.92-0.96; 95% CI, 0.89-0.99) and tau pathology (AUC, 0.93-0.97; 95% CI, 0.84-0.99) across all cohorts, whose accuracy was comparable with CSF biomarkers in determining abnormal PET signal.

Longitudinally, data further showed, plasma p-tau217 values displayed an annual increase in amyloid-beta-positive individuals only, with the highest increase observed in those positive for tau.

“These results emphasize the important role of plasma p-tau217 as an initial screening tool in the management of cognitive impairment by underlining those who may benefit from antiamyloid immunotherapies,” Ashton and colleagues wrote.