September 6, 2026

@michaelokun

What resonates with me about the recent FDA clearances of blood tests for Alzheimer’s disease is that we are crossing an important threshold: biomarkers that largely lived in research studies and specialty centers are rapidly moving into everyday clinical practice. Four FDA-cleared blood-based assays are now available, including two cleared in August 2026, with p-tau217 emerging near the center of this new diagnostic pathway. But clinicians need to understand that ordering the test may be the easy part; managing what comes next will be harder. These are tests for the likelihood of amyloid pathology, not stand-alone tests that diagnose Alzheimer’s disease, and results must be interpreted in the context of the person’s symptoms, age, cognitive testing, comorbidities and pretest probability. A negative result may help some patients avoid more invasive or expensive testing, while intermediate or positive results may lead to amyloid PET or CSF confirmation and potentially consideration of disease-modifying therapy. We also need to think carefully about false positives, particularly when testing people in lower-prevalence populations, and about the counseling required before and after testing. The blood test should therefore never replace the clinician or the clinical history. It should make us better clinicians by helping us put the right patient on the right diagnostic pathway at the right time.