Blood-based Biomarkers for Alzheimer's Disease: Positioning Document and Usage Recommendations from the Behavioral Neurology and Dementia Study Group of the Spanish Society of Neurology

Introduction: The development of blood biomarkers for detecting Alzheimer's disease (AD) represents one of the most significant recent advances, and some are already available for clinical practice. Therefore, the Grupo de Estudio de Conducta y Demencias de la Sociedad Española de Neurología has formed a working group to review the current status and develop consensus recommendations for their clinical implementation.

Development: This document was prepared by neurologists from the Grupo de Estudio de Conducta y Demencias de la Sociedad Española de Neurología in two phases. First, a coordinating group defined the basic guidelines of the document, agreed on initial recommendations based on a literature review, and drafted a preliminary version. Subsequently, the proposal was reviewed by the entire working group, all comments were considered, and the coordinating group adjusted the recommendations until consensus was achieved among the participants.

Conclusions: The consensus document highlights the importance of early diagnosis of AD. It recommends interpreting blood biomarkers in the patient's clinical context, not in isolation. Specialized units can start using them, but this should be accompanied by ongoing research. More data are needed for their use in general neurology and primary care. Their use is not recommended in asymptomatic individuals, population screenings, or as direct-to-consumer tests. Public health systems should facilitate their implementation through appropriate funding to ensure equitable access. This document should be understood as an initial framework subject to periodic updates as new data emerge.