In a pilot study, researchers found a good correlation of p-tau217 levels from blood obtained via standard venous sampling and from a single finger prick.
“We see the potential that capillary p-tau217 from dried blood spots could overcome the limitations of standard venous collection of being invasive, dependent on centrifuges and ultra-low temperature freezers, and also requiring less volume than standard plasma analysis,” said lead investigator Hanna Huber, PhD, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, University of Gothenburg, Sweden.
The findings were presented at the 17th Clinical Trials on Alzheimer’s Disease (CTAD) conference.
Strong Link Between Venous and Capillary Samples
p-tau217 has emerged as the most effective blood test to identify Alzheimer’s disease. However, traditional venous blood sampling requires certain infrastructure and immediate processing. Increased and simplified access to this blood biomarker could be crucial for early diagnosis, proper patient management, and prompt initiation of disease-modifying treatments.
The DROP-AD project is investigating the diagnostic performance of finger-prick collection to accurately measure p-tau217. In the current study, the research team obtained paired venous blood and capillary blood samples from 206 adults (mean age, 71.8 years; 59% women), with or without cognitive impairment, from five European centers. A subset of participants provided a second finger-prick sample collected without any supervision.
The capillary blood samples were obtained via a single finger prick, and then single blood drops were applied to a dried plasma spot (DPS) card, which was then shipped to a lab (without temperature control or cooling) for p-tau217 measurement. Cerebrospinal fluid biomarkers were available for a subset of individuals.
Throughout the entire study population, there was a “very convincing correlation” between p-tau217 levels from capillary DPS and venous plasma, Huber told conference attendees.
Additionally, capillary DPS p-tau217 levels were able to discriminate amyloid-positive from amyloid-negative individuals, with levels of this biomarker increasing in a stepwise fashion, “from cognitively unimpaired individuals to individuals with mild cognitive impairment and, finally, to dementia patients,” Huber said.
Of note, capillary p-tau217 levels from DPS samples that were collected by research staff did not differ from unsupervised self-collected samples.
What about the stability of the samples? Capillary DPS p-tau-217 is “stable over 2 weeks at room temperature,” Huber said.
Ready for Prime Time?
Preliminary data from the DROP-AD project highlight the potential of using finger-prick blood collection to identify neurofilament light (NfL) and glial fibrillary acidic protein (GFAP), two other Alzheimer’s disease biomarkers.
“We think that capillary p-tau217, but also other biomarkers, could be a widely accessible and cheap alternative for clinical practice and clinical trials in individuals with cognitive decline if the results are confirmed in longitudinal and home-sampling cohorts,” Huber concluded.
“Measuring biomarkers by a simple finger prick could facilitate regular and autonomous sampling at home, which would be particularly useful in remote and rural settings,” she noted.
The findings in this study confirm and extend earlier findings that the study team reported last year at the Alzheimer’s Association International Conference (AAIC).
“The data shared at CTAD 2024, along with the related material previously presented at AAIC 2023, reporting on a ‘finger prick’ blood test approach is interesting and emerging work but not yet ready for clinical use,” said Rebecca M. Edelmayer, PhD, Alzheimer’s Association vice president of scientific engagement.
“That said, the idea of a highly accessible and scalable tool that can aid in easier and more equitable diagnosis would be welcomed by researchers, clinicians, and individuals and families affected by Alzheimer’s disease and all other dementias,” Edelmayer said.
“This finger-prick blood testing technology for Alzheimer’s biomarkers still has to be validated more broadly, but it is very promising. Advancements in technology and practice demonstrate the simplicity, transportability, and diagnostic value of blood-based biomarkers for Alzheimer’s,” she added.
The Alzheimer’s Association is currently conducting a systematic review of the evidence and preparing clinical practice guidelines on blood-based biomarker tests for specialized healthcare settings, with publications, clinical resources, and tools anticipated in 2025, Edelmayer noted.
The study had no commercial funding. Huber and Edelmayer report no relevant conflicts of interest.
A version of this article appeared on Medscape.com.