Amyloid Positron Emission Tomography Improves Diagnosis, Management of Alzheimer Disease

A recently published study suggests amyloid positron emission tomography alongside routine cognitive impairment assessment may improve physicians’ diagnosis and management of Alzheimer disease. 

“Brain ß-amyloid is a hallmark of Alzheimer disease (AD) and is quantifiable in vivo through specific positron emission tomography (PET) radiotracers binding to ß-amyloid,” Marina Boccardi, PhD, of the LANVIE-Laboratory of Neuroimaging of Aging at the University of Geneva, and colleagues wrote in JAMA Neurology. “However, the clinical utility of amyloid PET is still under investigation worldwide. … Consequently, amyloid PET, although approved for clinical use, is still not reimbursed by national health care systems.” 

Dr Boccardi and colleagues evaluated the diagnoses of 228 cogitatively impaired adults (mean age = 70.5 years) at 18 Italian AD evaluation units. Prior to the amyloid PET intervention, physicians performed routine clinical and instrumental assessment, including diagnosis, drug treatment, and physicians’ self-reported confidence in their diagnosis. Physicians then reviewed the scan’s results and received an opportunity to amend their decisions and again report their confidence.

The researchers observed diagnostic changes in 79% of patients with prior AD diagnosis and negative scan (P < .001) and 53% of patients with non-AD diagnosis and positive scan (P < .001). Physicians’ diagnostic confidence increased with positive scans but decreased with negative scans. Physicians initiated medication in 65.6% of patients with positive scans but no treatment, and discontinued medication in 33.3% of those receiving treatment before a negative scan.

The results of this study provide evidence of the diagnostic capabilities of amyloid PET and its potential role in differentiating between AD and other treatable cognitive conditions, but do not yet provide a clear case for clinical utility and, consequently, insurer coverage, according to Richard J Caselli, MD, and Bryan K Woodruff, MD, both of the neurology department at the Mayo Clinic Arizona. 

“Amyloid PET scans are expensive: €2000 in Italy and $4000 in the United States,” the experts wrote in an accompanying editorial. “Does the ability to modestly increase diagnostic confidence in distinguishing between several equally degenerative diseases and, in turn, jockey marginally effective symptomatic medications justify this added cost to an already expensive disease? Although there may remain room for argument about cost, the findings of Boccardi and colleagues provide important insight.” —Dave Muoio