[Potential of Blood Biomarkers for Early Diagnosis of Dementia]

Blood biomarkers represent a major breakthrough in the early diagnosis of Alzheimer's disease (AD). Plasma p-tau217/Aβ42 ratio demonstrates diagnostic accuracy comparable to PET and CSF examinations, leading to FDA approval of the first blood-based AD test in May 2025. With insurance coverage now extending to disease-modifying therapies such as lecanemab and donanemab at the mild cognitive impairment (MCI) stage, the clinical adoption of these minimally invasive diagnostic tools is rapidly advancing. Current development includes Core 1 biomarkers (A: Aβ proteinopathy, T1: phosphorylated tau) and emerging Core 2 biomarkers (T2: tau proteinopathy), with novel assays such as mid-p-tau181 showing promise. However, its application to asymptomatic individuals in brain dock settings remains challenging due to ethical considerations, including psychological burden and the uncertainty of predicting disease progression. Future directions include integrating digital biomarkers to enhance diagnostic accuracy and generating evidence for long-term healthcare benefits, while addressing standardization across manufacturers and implementing dual-cutoff strategies to optimize clinical utility.