Alzheimer’s Disease blood biomarkers measured through remote capillary sampling correlate with cognition in older adults

Blood biomarkers are rapidly becoming established for Alzheimer's Disease (AD) diagnosis. However, there is a need for more scalable tools to reach the 99% of individuals with early cognitive impairment who are not seen in specialist healthcare services. A recent study validated a capillary blood sampling technique to detect the p-tau217 and GFAP biomarkers. Here we used our PROTECT research study to show that these biomarkers, when collected using self-administered fingerprick tests, correlate well with venous blood biomarkers and with cognition and function in 174 people who were cognitively normal or who had mild cognitive impairment or AD. They can be used in combination with computerised cognitive testing to identify people with the highest risk of AD. The GFAP biomarker appears to be associated with vascular risk, unlike p-tau217. Patient feedback indicates high acceptability and usability of the capillary test method, giving confidence in the feasibility of this technology. The work suggests that capillary blood biomarkers could be used to enable triage of people with varying levels of risk of AD in clinical practice and for clinical trials, and could be used outside of clinical settings.