By Vishnu Samara, PhD, DABCC
The diagnostic landscape for Alzheimer’s disease has evolved rapidly over the last couple of years. The recent approval of two new drugs to treat the disease ─ lecanemab and donanemab ─ has intensified interest in detecting Alzheimer’s as early as possible, leading to the development of blood-based biomarkers, approval for reimbursement through the Centers for Medicare & Medicaid Services, and the creation of specific diagnostic codes.
In today’s session, titled, “Revised criteria for diagnosis and staging: An update on blood-based biomarkers in Alzheimer’s disease and other dementia,” two experts make the case that now the time to introduce blood-based biomarkers for Alzheimer’s pathophysiology into clinical laboratories.
Moderated by Hans Frykman, PhD, MSc, MD, FRCPC, the session will cover the state-of-the-art on Alzheimer's testing. Considering the complexity of Alzheimer’s and other forms of dementia, the use of biomarkers represents a major advance, given that the standard methods for diagnosis include PET imaging and a painful spinal tap to measure amyloid in cerebral spinal fluid.
Frykman, a professor at the University of British Columbia, will present his perspective from a clinical laboratory standpoint, providing clinical interpretations of these blood-based biomarkers based on real case examples. Frykman thinks the growing use of these biomarkers for Alzheimer’s can be seen as comparable to the adoption of troponin measurement for assessing myocardial infarctions.
Henrik Zetterberg, MD, PhD, a neurochemist from the University of Gothenburg, Sweden, believes the currently available assays produce clinically reliable results. He will argue that the biomarkers should be made part of the basal evaluation of patients with memory complaints. A two-cutoff approach that indicates if patients are at high, indeterminate, or low risk of Alzheimer's disease seems to be working best, according to Zetterberg.
Frykman will share his experience validating the p-Tau 217 assay from a very large sample of deceased Alzheimer’s patients (confirmed by PET scan) along with healthy controls. The session will cover other tests, such as NfL, GFAP, MTBR, and Tau433, and describe how to combine them for diagnosing a range of neurodegenerative diseases. Frykman’s research showed that pTau217 performed very well compared to other tests and is very specific for the amyloid pathology that exists in Alzheimer’s.
However, as these tests are increasingly used in clinical practice, they will undoubtedly bring challenges as well as advantages, considering that this is the first generation of pTau217. The session will help ADLM 2025 attendees understand that specific plasma p-tau217 assays may require distinct decision points for Alzheimer’s screening, diagnosis, and disease-progression monitoring. The speakers will also discuss the global biomarker standardization consortium (Alzheimer's Association GBSC) and how members of the laboratory medicine community can contribute to it meaningfully.
