Fluid Biomarkers in Dementia Diagnosis

This article discusses how fluid biomarkers can augment the routine dementia evaluation and improve diagnostic accuracy. The tests that are currently available and the indications for their use are described. Further, tests that are under development and likely to be used in the future are identified.

Technical improvements in assay sensitivity and precision have led to the rapid development of blood-based biomarkers for Alzheimer disease (AD) over the past several years. Studies have found that the ratio of amyloid-β (Aβ) peptides (Aβ42/Aβ40) and concentrations of phosphorylated tau isoforms in plasma can identify individuals with AD brain pathology. Blood-based tests may enable much broader use of AD biomarkers in the evaluation of patients with cognitive impairment.

Even after a detailed history, examination, routine laboratory testing, and brain imaging, the cause of dementia sometimes remains unclear. CSF and blood-based biomarkers can evaluate for a range of neurologic disorders that are associated with dementia, including AD. Integrating data from fluid biomarker tests and the routine dementia evaluation may improve the accuracy of dementia diagnosis.