Neuropathology Core Abstract The goal of the Neuropathology Core (NP) is to support research on aging and dementia in DS by systematically collecting, characterizing and disseminating tissues from brain autopsies from clinically characterized participants enrolled in ABC-DS. The NP Core component to the ABC-DS study will provide a final neuropathology diagnosis, perform post-mortem MR imaging, obtain high quality tissue for research purposes, provide an infrastructure for the dissemination of tissue, neuropathology and imaging data and interact with all cores in the ABC-DS. In addition to newly collected brains, in the first 2 years of the study, the NP Core will characterize a legacy cohort of autopsy cases (n=65) to fill in gaps in neuropathology data and acquire novel outcomes. The NP Core will provide critical data in support of Projects 1, 2 and 3. The postmortem imaging data will facilitate the translation of in vivo imaging to neuropathology in a systematic manner. Thus, the NP Core will 1) develop a brain autopsy network, 2) provide neuropathology diagnoses and contribute data to the Biostatistics and Data Management Core; 3) Serve as a repository for tissue and disseminate tissue samples; 4) acquire and share whole slide quantitative digital pathology in support of Projects 1, 2 and 3; 5) acquire post mortem neuroimaging to bridge the gap between in vivo and ex vivo autopsy studies.