Blood
Alzheimer’s: At-home finger-prick blood test may aid earlier diagnosis
Jul
- Researchers found that finger prick tests may be effective for diagnosing and monitoring Alzheimer’s disease remotely.
- Another study found that blood tests deliver over 85% accuracy in Alzheimer’s diagnosis, whereas primary care physicians have around 55% accuracy.
- Blood tests may both increase the accuracy and accessibility of Alzheimer’s disease diagnosis and monitoring.
Around 6 million people in the U.S. currently live with Alzheimer’s disease. By 2050, this figure is projected to increase to almost 13 million.
While there is currently no cure for Alzheimer’s, studies show that early diagnosis and intervention are crucial for delaying its onset.
Current diagnostic methods include magnetic resonance imaging (MRI), cognitive tests, and physical exams. However, they have restricted accessibility as they require visiting a clinic with trained personnel and complex delivery and storage procedures for samples.
The accuracy of such tests also varies. A study found that around 25% of patients clinically diagnosed with probable Alzheimer’s during their lifetime did not have evidence of Alzheimer’s at autopsy.
Research also shows that up to 50% of patients with any form of dementia are not formally diagnosed while alive.
Improving the accuracy and availability of Alzheimer’s testing could help physicians diagnose the disease sooner and prescribe interventions to potentially delay disease progression.
Recently, researchers designed a method to analyze finger prick tests for Alzheimer’s that can be taken at home without the need for clinician oversight.
Another study found that blood tests can yield over 85% accuracy in detecting Alzheimer’s, whereas standard physical examinations deliver accurate diagnoses around 55% of the time.
The findings were presented at the Alzheimer’s Association International Conference in Amsterdam, Netherlands, and online.
For the study, the researchers included 77 memory clinic patients in Barcelona, Spain. All participants provided venous and finger prick blood samples as well as neuropsychological measures.
Blood samples were either spotted and dried on ‘dry blood spot’ (DBS) cards or preserved via an anticoagulant called ethylenediamine tetraacetic acid (EDTA) for overnight shipment to the University of Gothenburg in Sweden.
Whereas EDTA blood samples need to be refrigerated, DBS cards only require shelter from humidity and moisture, making them easier to transport. EDTA samples also require centrifugation—the mechanical separation of fluids according to their density—before they can be examined, whereas DBS does not require this step.
Once in Sweden, the researchers tested the blood samples for Alzheimer’s-related biomarkers, including neurofilament light (NfL), glial fibrillary acidic protein (GFAP), and phosphorylated tau.
They noted that Alzheimer’s biomarkers were present in all of the blood samples.
They wrote that this means that Alzheimer’s biomarkers can be quantified via finger prick collection and that DBS could help with regular monitoring of patients with suspected neurological conditions.
In a second study also to be presented at the Alzheimer’s Association International Conference, Dr. Sebastian Palqvist, Ph.D., associate professor at Lund University, Sweden, and colleagues compared the efficacy of blood-based biomarkers for detecting Alzheimer’s with examinations from primary care physicians.
They included 307 middle-aged to elderly patients with an average age of 76 years. Primary care exams included cognitive testing and a CT or MRI scan. Participants also provided a venous blood sample which was analyzed to determine concentrations of beta-amyloid and phosphorylated tau.
Whereas primary care physicians identified Alzheimer’s-related changes or correctly diagnosed Alzheimer’s 55% of the time, blood tests did so over 85% of the time.
Dr. Palmqvist said in a press release that a lack of accurate diagnostic tools could make it difficult for primary care doctors to identify Alzheimer’s.
“This too often leads to diagnostic uncertainty and inappropriate treatment. Blood tests for Alzheimer’s have great potential for improving diagnostic accuracy and proper treatment of people with Alzheimer’s. These tests may become even more important in the near future, as new drugs that slow down the disease in its early stages become more widely available,” he added.
“We see these new tools improving our ability to recognize the earliest changes of Alzheimer’s and ultimately speeding our ability to prevent or delay the onset of memory decline,” Dr. Jeffrey Burns, neurologist and co-director of the University of Kansas Medical Center’s Alzheimer’s Disease Research Center, who was not involved in the study, told Medical News Today.
“These tools will become available to the public soon. We expect FDA approval of blood measures of Alzheimer’s in the next 1 to 2 years. We are entering a new and exciting era of Alzheimer’s disease with new diagnostic and treatment approaches that will change how we practice dramatically.”
— Dr. Jeffrey Burns
“Currently, there’s a bottleneck where we don’t have enough specialty clinicians to do the extensive testing needed to diagnose Alzheimer’s,” Dr. David Merrill, Ph.D., psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center in Santa Monica, California, who was not involved in the study, told MNT.
“Radioactive brain scans and lumbar puncture tests are riskier, more expensive, and require specialty medical care. Even the current blood tests need expert processing and handling to not spoil the results,” he explained.
“If this method is validated, it could increase the number of patients screened for Alzheimer’s and may help catch the disease early, when interventions can have a greater impact,” Dr. Jennifer Bramen, Ph.D., a senior research scientist at the Pacific Neuroscience Institute in Santa Monica, California, who was also not involved in the study, told MNT.
“A simple finger prick of blood put onto a card that can be shipped directly from a patient’s home at room temperature simplifies the process of getting tested for Alzheimer’s.”
— Dr. David Merrill
Dr. Bramen noted that a limitation to the findings is that it was a small pilot study, and the research methods and results have not yet been through the peer-review process.
Dr. Burns added that detecting amyloid is not the same as Alzheimer’s.
“It will be important to learn how best to apply these tools in broad, real-world clinical practice,” he said.
MNT also spoke with Dr. Raphael Wald, Psy.D., a neuropsychologist at Baptist Health Marcus Neuroscience Institute, who was not involved in the study. He noted that while the test may be useful as corroborative evidence for diagnosing Alzheimer’s, it does not indicate the level of impairment a person has.
“Some people show evidence of Alzheimer’s through other tests and can manage their daily lives quite well. Others have no signs of Alzheimer’s and are quite impaired,” he explained.
Meanwhile, Dr. Merrill said that while blood tests may be more accurate than taking medical histories alone, clinicians must also consider what care comes afterward.
“Will there be ready access to confirmatory testing? How often can or should the test be repeated and who will pay for it? Will blood spot testing be accepted for beginning treatments or will more tests be required? What support will be in place for newly diagnosed patients? The diagnosis of Alzheimer’s can be a devastating moment. There’s a lot of details to work through before offering this test to the general public,” he concluded.
