July 20, 2023 -- A finger-prick blood test can accurately identify key Alzheimer's disease biomarkers without the need for temperature or storage control measures, results of a new study suggest.
The use of blood samples to detect amyloid and other markers of Alzheimer’s has become standard procedure for monitoring patients in clinical trials. But this presents logistical challenges because it requires strict, time-limited, temperature-dependent protocols.
To make this process more efficient, the researchers conducted a pilot study that investigated a new way of detecting them by dropping a small blood sample onto a blood spot card, where it dries and remains at room temperature.
To investigate the accuracy of the test, the investigators recruited 77 volunteers who were attending a memory clinic in Barcelona. Whole blood samples were obtained using traditional needles and syringes and also from a finger prick, similar to diabetes blood testing.
In a subset of 28 patients, the investigators also obtained cerebrospinal fluid samples, found in the tissue that surrounds the brain and spinal cord, which represent the "absolute gold standard of AD diagnostics," study co-investigator Nicholas Ashton, PhD, associate professor at the Institute of Neuroscience and Physiology, University of Gothenburg in Sweden, said.
The blood samples were shipped overnight without temperature control or cooling to Gothenburg, where they were extracted from the blood spot cards and tested for the presence of Alzheimer’s biomarkers.
Results showed an "extremely good relationship" between information from blood obtained through the normal method and that from a single finger prick.
The findings were presented at the Alzheimer's Association International Conference (AAIC) 2023.
"We're saying we can measure … established markers for AD, all in a single finger prick, which means you don't need to do centrifugation, you don't need to freeze the sample, it can be done anywhere," said Ashton.
If the test is validated in larger trials, it could mean that in the future, patients with memory complaints could be tested remotely by completing a standard memory test online and using a mail-in blood spot card.
Not only could this potentially make earlier diagnosis easier, but it could also be used to regularly monitor treatment response. Ashton said this is especially important now that disease-modifying drugs are becoming available.
"If you're receiving one of these treatments, you can send tests back to a laboratory to see how you're progressing on the drug,” he said. “It isn't just a blanket 6-month check-up when you're on a drug; it can be followed on a weekly basis and personalized to the person who is on the medicine."
The study shows the samples remain stable for up to a month at room temperature, which is "really encouraging," although there are still some challenges with unsupervised blood collection, said Ashton.
Timely, Important Research
Commenting on the research, Percy Griffin, PhD, director of scientific engagement for the Alzheimer's Association, said the fact that the study showed that finger-prick blood samples can be dried and shipped overnight without temperature control might lead to earlier and more accurate diagnoses in areas with relatively few resources. In addition, this type of test could facilitate easier monitoring of high-risk patients receiving therapies, he said.
However, he noted that it is a pilot study, and the results need to be replicated.
The blood tests were more accurate in identifying Alzheimer’s than were primary care doctors, so these results are important. Inaccuracy "all too often leads to uncertainty and potentially inappropriate treatment," Griffin said.
"So again, this is showing the great potential of blood tests to improve diagnostic accuracy and appropriate treatment."