Performing multiple biomarker tests delays initiation of amyloid-targeting treatments

With the clinical availability of amyloid-targeting treatments (ATTs), accurate and timely biomarker-based diagnosis of Alzheimer's disease (AD) has become increasingly important. Three AD biomarker modalities are commonly available in clinical practice: amyloid positron emission tomography (PET), cerebrospinal fluid (CSF) tests, and blood tests.

We investigated the use and agreement of different biomarker modalities in a memory clinic. Further, we calculated the time until ATT initiation for patients who underwent a single test versus multiple biomarker tests.

The blood test agreed with amyloid PET in nine of 11 patients and CSF tests in all 14 patients. The median time from first clinic visit to ATT initiation was 4.7 months in 209 patients who underwent a single test and 8.1 months in 12 patients who underwent multiple tests.

Performing multiple biomarker tests delays initiation of ATT and should be restricted to patients with uncertain amyloid status following the first biomarker test.