Researchers: Finger-prick blood test could offer easier way to detect Alzheimer’s

A finger-prick blood test that can be mailed to a lab may offer a simpler way to detect the brain changes linked to Alzheimer’s disease, according to a new study.

Researchers tested whether tiny samples of blood dried onto paper cards — similar to those used in newborn heel-prick screenings for rare, but serious inherited conditions — could reliably measure biomarkers linked to the memory-robbing disease. The approach avoids needles, centrifuges and refrigerated transport, all of which complicate current testing and limit its use outside specialist clinics.

The key finding reported Monday, Jan. 5, in the journal Nature Medicine was that levels of phosphorylated tau-217, a leading blood marker of Alzheimer’s disease, tracked closely between dried samples and conventional blood tests. Higher levels of the marker were linked to worse cognition and to Alzheimer’s-related changes seen in spinal fluid.

Tests using the dried samples were less accurate than traditional blood ones, but still showed good ability to distinguish people with Alzheimer’s-related disease.

Dried blood analysis offers a “feasible and scalable” way to detect the brain changes linked to Alzheimer’s in research and population studies, the authors wrote. Still, they cautioned that the minimally invasive method isn’t yet accurate enough to use in routine patient care.

Alzheimer’s disease affects tens of millions of people worldwide, a number expected to rise sharply as populations age. Diagnosis remains expensive and uneven, often relying on brain scans or spinal taps that are invasive and costly.

Although new drugs that target the underlying biology of Alzheimer’s have reached the market, their benefits are modest and they work best when the disease is detected early. Cheaper, simpler testing could help identify patients sooner, expand access to clinical trials, and improve understanding of how widely Alzheimer’s-related brain changes are spread in the population.

The study followed 337 people across seven European centers, including individuals with normal cognition, mild cognitive impairment and Alzheimer’s. Participants provided both standard blood samples drawn from a vein and capillary blood collected by finger prick and dried on cards. In a subset, spinal fluid samples were also available for comparison.

The researchers also showed that two other markers — glial fibrillary acidic protein, which reflects brain inflammation, and neurofilament light, a marker of nerve damage — could be measured reliably from dried blood, indicating potential uses beyond Alzheimer’s in conditions such as multiple sclerosis and amyotrophic lateral sclerosis.

Importantly, the team found little difference between samples collected by trained staff and those collected by participants themselves, suggesting the method could work outside clinical settings. That could make large-scale and remote studies easier, including in people with Down syndrome, who are at high genetic risk of developing Alzheimer’s, and other populations that are harder to reach with conventional testing.