For decades, there have been differences of opinion about when any particular diagnostic test is "medically necessary," and there's a new case study today. It's an article from UCSF and appears in JAMA Internal Medicine.
In the past couple years, there has been an explosion of interest in blood-based tests to help make the diagnosis of Alzheimer's disease. It's driven in part by the availability of Alzheimer- or amyloid-specific drugs, but also by substantial improvements - finally - in the clinical chemistry of proteomics for the related proteins. See an an article by Palmqvist et al. in JAMA 2024, and revised biomarker-based diagnostic criteria also from Alzheimer Association Workgroup, 2024, Jack et al. Those are just two landmarks; it's a booming area of publications.
See a new opinion in the reverse direction, by Widera & Covinsky, in JAMA Internal Medicine, May 12. The authors are at UCSF Geriatrics and the SF VA, and Covinsky is a JAMA editor as well.
They open by citing "a recent television commercial..directs viewers to a disease awareness website." This leads to "the allure of early detection" but "clinicians should be wary." But, the topic is not just driven by TV commercials; it's a wide range of research publications and expert consensus publications. Recognizing this, the authors add, "Recent efforts to redefine the diagnosis of Alzheimer disease from a clinical-pathological construct that starts with symptoms to a purely biological one that potentially begins with a laboratory test are deeply problematic if incorporated into current clinical care. ... Enthusiasm should be tempered."
Without taking sides, I'll note that some of their points are:
- Subjective complaints are common with normal aging.
- Diagnosis should not be made on subjective comlaints or an abnormal test.
- Diagnosis requires comprehensive evaluation.
- Cognitive dysfunction is a syndrome, not a cause.
- Alzheimer pathology does not imply dementia; many with neuropathology [biomarkers] do not progress to disease.
- Risk of overdiagnosis = anxiety and worse.
- Blood based biomarkers should be used in the same cases, where you would have used an amyloid PET scan.
