Fluid Biomarkers in Dementia Diagnosis.

Objective: This article familiarizes neurologists with the currently available CSF and plasma biomarkers for the diagnosis of dementia and diagnosis-dependent treatment decisions.

Latest Developments: For Alzheimer disease, the recent US Food and Drug Administration (FDA) approval of monoclonal antibody therapy has increased the urgency of confirming the pathologic diagnosis with biomarkers before initiating therapy. The new availability of disease-modifying therapies also highlights the need for biomarkers to monitor efficacy over time. Both of these needs have been partially addressed by the emergence of improved blood-based biomarkers for Alzheimer disease. Regarding other forms of dementia, the latest development is a CSF assay for aggregated α-synuclein, which permits the biomarker confirmation of synuclein pathology in Lewy body dementia.

Essential Points: CSF biomarkers for the diagnosis of Alzheimer disease, Lewy body dementia, and Creutzfeldt-Jakob disease are well established. Blood-based biomarkers for dementia diagnosis are emerging and rapidly evolving. Sensitivity and specificity for diagnosis continue to improve, and they are being incorporated into diagnostic decisions. Fluid biomarkers for monitoring the efficacy of therapy are not yet established. Because serial CSF examinations are impractical, the validation of blood-based biomarkers of disease activity will be critical for addressing this unmet need.