SUMMARY
# FTLD-Tau vs FTLD-TDP In Vivo Biomarker Differentiation
## Background and Rationale
This comprehensive clinical study addresses a critical need in frontotemporal lobar degeneration (FTLD) research by developing biomarkers to differentiate between tau-positive (FTLD-Tau) and TDP-43-positive (FTLD-TDP) pathological subtypes during life. Current clinical criteria cannot reliably distinguish these subtypes, which have different underlying molecular mechanisms, genetic risk factors, and potentially
METHODOLOGY NOTES
**Phase 1: Patient Recruitment and Clinical Characterization (Months 1-6)**
Recruit 150 participants: 50 FTLD-Tau patients, 50 FTLD-TDP patients, and 50 age-matched healthy controls. Inclusion criteria include clinical diagnosis of FTLD based on consensus criteria, age 45-85 years, and availability of genetic testing results. Exclusion criteria include significant psychiatric comorbidities, recent immunosuppressive therapy, or contraindications to lumbar puncture or PET imaging. Conduct comprehensive neuropsychological assessment using Frontotemporal Lobar Degeneration-Clinical Dementia Rating (FTLD-CDR), Neuropsychiatric Inventory (NPI), and Frontal Behavioral Inventory (FBI).
**Phase 2: Multimodal Biomarker Collection (Months 3-12)**
Collect CSF via lumbar puncture for tau species analysis using ultrasensitive immunoassays (Simoa platform). Measure 4R-tau, 3R-tau, phospho-tau181, phospho-tau217, and TDP-43 levels. Perform [18F]MK-6240 tau-PET and [18F]AV-1451 imaging with quantita