What Does a Positive Alzheimer Disease Blood-Based Biomarker Result Mean in People With Mild Cognitive Impairment?

Blood-based biomarkers (BBMs) for Alzheimer disease (AD) offer widely expanded access to biomarker-informed diagnoses in community settings that have previously lacked such resources. However, integrating them into current clinical diagnostic practice presents challenges, particularly in the diagnosis of mild cognitive impairment (MCI). Limited data are available to guide clinicians on when to test, how to counsel patients with MCI and a positive AD BBM result about their risk of dementia progression, or which evidence-based dementia prevention strategies or treatments to recommend. This Perspective article outlines the key challenges faced by clinicians and patients when addressing a diagnosis of "MCI due to AD" and offers suggestions for appropriate pretest counseling and future research directions to address current knowledge gaps.