A blood-based biomarker test measuring a protein called p-tau217 significantly improved the accuracy of Alzheimer’s disease diagnosis in routine clinical practice, according to a study published in the Journal of Neurology.
Researchers in Spain followed 200 consecutive patients aged 50 and older who presented with cognitive symptoms at both general neurology and specialist cognitive neurology units. Clinicians recorded their initial diagnosis and confidence level before and after reviewing p-tau217 blood test results.
P-tau217 is a form of tau protein that, when abnormally phosphorylated, accumulates in the brain and disrupts communication between neurons, a process associated with Alzheimer’s disease. Elevated blood levels of p-tau217 have been identified as a reliable early indicator of the condition.
When relying on standard clinical evaluation alone, diagnostic accuracy for Alzheimer’s stood at 75.5%. After incorporating the blood test results, this rose to 94.5%. For approximately one in four patients, the test prompted a change in diagnosis; some initially suspected of having Alzheimer’s were found to have a different condition, while others attributed to normal ageing were correctly identified as having the disease. Clinicians’ average confidence in their diagnoses also increased notably following the test.
The findings held across all stages of cognitive decline, from early subjective memory complaints to more advanced presentations such as dementia.
The authors note that current standard diagnostic methods, including brain imaging and cerebrospinal fluid analysis, are costly and invasive. A blood-based test could offer a more accessible alternative, though further validation across diverse populations and clinical settings would be needed before broader implementation.
