CTSD and Alzheimer disease: Our epigenetic analysis leveraging both blood and brain omics identified potentially distinct epigenetic regulatory mechanisms between the periphery and the dorsolateral prefrontal cortex underlying IR and AD at cg15150970 (DNMT3A), cg22948094 (CTNNB1), cg12729894 (CTSD), cg00574958 and cg17058475 (CPT1A).