KLK6 and Alzheimer disease: We focused on proteins that have been linked to both brain aging and AD in our analysis (NEFL, GFAP, KLK6, BCAN, SYT1 and CNTN1), as well as proteins potentially implicated in AD pathology (MAPT (tau), APP and APPL2) or prioritized in previous studies (GDF15 (ref. 31) and NRXN3 (ref. 3)).