Blood Tests Could Improve Diagnosis of Alzheimer’s Disease, Reduce Diagnosis and Treatment Wait Times

As highly accurate blood tests for Alzheimer’s disease move closer to approved use in physician’s offices, new research suggests that they may revolutionize the accuracy of diagnosis and provide a cleaner, quicker path to diagnosis and treatment, according to data reported at the Alzheimer’s Association International Conference 2024 in Philadelphia.
Dementia is often underdiagnosed – and if it is diagnosed by a clinician, many people are still unaware or uninformed of their diagnosis, according to the 2024 Alzheimer’s Disease Facts and Figures report. Blood tests for Alzheimer’s are demonstrating in research that they could significantly improve a clinician’s accuracy and confidence, provide greater accessibility and a platform for enhanced communication.
Blood tests that show the most promise for identifying Alzheimer’s-related changes in the brain assess phosphorylated tau (p-tau) protein, an Alzheimer’s biomarker that can build up before patients show signs of cognitive impairment. Increases in the specific marker p-tau217 over time correlate with worsening cognition and brain atrophy. The p-tau217 test also predicts the likelihood of amyloid plaques in the brain, which are another biomarker for Alzheimer’s and the target for recently approved treatments.
“Blood tests, once they (a) are confirmed in large populations to be more than 90% accurate and (b) become more widely available, show promise for improving, and possibly redefining, the clinical trial recruitment process and the diagnostic work-up for Alzheimer’s,” said Maria C. Carrillo, Ph.D., Alzheimer’s Association chief science officer and medical affairs lead. “While at this time doctors in primary and secondary care should use a combination of cognitive and blood or other biomarker testing to diagnose Alzheimer’s, blood tests have the potential to increase the accuracy of early diagnoses and maximize the opportunity to access Alzheimer’s treatments as early as possible for better outcomes.”
When considering use of a blood test, the Alzheimer’s Association Appropriate Use Recommendations for Blood Biomarkers in Alzheimer’s Disease should be carefully followed.
Blood Test Can Improve Diagnosis Among Primary Care and Alzheimer’s Disease Specialists
A large study, reported for the first time at AAIC 2024, shows that blood tests can do a better job of accurately detecting Alzheimer’s than both primary care doctors and specialists who were using traditional diagnostic methods.
In the study, 1,213 patients were tested with the PrecivityAD2 test (known as “APS2”).
Among 698 patients seen at memory clinics, APS2 was around 90% accurate at identifying Alzheimer’s disease while specialists were 73% accurate.
Among 515 patients seen in primary care, APS2 was also around 90% accurate; primary care physicians were 63% accurate at identifying Alzheimer’s.
Blood Tests Could Drastically Reduce Wait Times for Alzheimer’s Diagnosis and Treatment
Approved Alzheimer’s treatments are indicated for people with mild cognitive impairment due to Alzheimer’s or mild Alzheimer’s dementia, and they must have confirmed amyloid-beta biology in the brain. Therefore, it’s important to identify people who might benefit as early in the course of the disease as possible.
Right now, there are often lengthy wait times to complete comprehensive testing for an Alzheimer’s diagnosis due to the limited number of Alzheimer’s specialists and the growing aging population.
The model included the projected U.S. population of people 55 and older from 2023 to 2032. It suggests that by 2033, people will wait an average of nearly six years (70 months) to understand if they could be eligible for new Alzheimer’s treatments if their primary care doctor only used brief cognitive assessments to make referrals. If blood tests were used to rule out Alzheimer’s, the average wait times would be reduced to 13 months for Alzheimer’s patients because far fewer patients would need to see a specialist.
Researchers also determined that if blood tests and brief cognitive assessments were used at the primary care level to rule in the possibility of an Alzheimer’s diagnosis, wait times to understand eligibility for new treatments would fall to less than six months on average because of reduced demand for Alzheimer’s specialists and the additional capacity now available for CSF or PET testing.
“Our results suggest using blood tests to identify potential candidates for treatments could make a significant difference in treating people with early Alzheimer’s,” said Soeren Mattke, M.D., D.Sc., lead author of the study and director of the Brain Health Observatory, at the University of Southern California, Los Angeles. “Currently, eligible patients are falling outside of the treatment window because it takes so long to receive a diagnosis. An easy-to-use blood test could help address that problem.”
Nearly 7 million Americans aged 65 and older have Alzheimer’s dementia, including 38,100 in West Virginia. One in three seniors dies with the disease – more than breast and prostate cancer combined. West Virginia’s mortality rate of 47.7% from Alzheimer’s is significantly higher than the national mortality rate of 36%.
Those concerned about themselves or a loved one can contact the Alzheimer’s Association West Virginia Chapter at 304.343.2717 to schedule a care consultation and be connected to local resources. The Alzheimer’s Association’s Helpline can be reached 24/7 at 800.272.3900.