Down syndrome is a genetic form of Alzheimer's disease that offers crucial insights into Alzheimer's disease pathogenesis. The Down Alzheimer Barcelona Neuroimaging Initiative is a population-based multimodal biomarker cohort studying Alzheimer's disease's natural history and clinical trials in DS. DABNI participates in Alzheimer's disease clinical trials and produced approximately 100 publications. The 10-year DABNI study provided critical insights into DS-associated Alzheimer's disease and serves as a key platform for DS clinical trials. HIGHLIGHTS: Down Alzheimer Barcelona Neuroimaging Initiative is a population-based multimodal cohort studying Alzheimer's disease in Down syndrome. DABNI supports clinical trials and has produced over 100 publications advancing Down syndrome-related Alzheimer's research.