Down Syndrome Alzheimer's Disease: Mechanisms and Therapeutic Timing

SUMMARY

# Down Syndrome Alzheimer's Disease: Mechanisms and Therapeutic Timing ## Background and Rationale This study investigates the mechanistic link between trisomy 21 and inevitable Alzheimer's pathology in Down syndrome, focusing on the therapeutic window for intervention. Nearly 100% of DS individuals develop AD neuropathology by age 40, primarily due to APP gene triplication on chromosome 21. **Protocol**: Multi-center longitudinal study of 300 DS individuals (ages 25-50) stratified by cognitive

METHODOLOGY NOTES

**Phase 1: Patient Recruitment and Baseline Assessment (Months 1-6)** • Recruit 200 adults with Down syndrome (ages 30-65) from specialized care centers • Include 100 age-matched neurotypical controls for biomarker comparisons • Obtain informed consent from participants and/or legal guardians • Conduct comprehensive neuropsychological assessment using DS-specific batteries (CAMCOG-DS, DAMES) • Perform brain MRI with volumetric analysis and DTI sequences • Collect CSF samples for Aβ42, tau, p-tau181, and neurofilament light measurements • Draw blood for APOE genotyping, inflammatory markers, and plasma biomarkers **Phase 2: Longitudinal Monitoring (Months 6-36)** • Conduct assessments every 6 months including cognitive testing and clinical evaluations • Perform annual brain MRI to track structural changes • Collect CSF samples annually for biomarker progression analysis • Monitor participants for emergence of dementia symptoms using CDR-SB and FAST scales • Track medication changes and