Oxidations, the most common modifications (typically 25–44% of total hits), increased nearly threefold in AD relative to normal controls (>1.7‐fold even after adjusting for 66% more aggregates observed in AD), in both Aβ1–42‐ and tau‐affinity aggregates (for each IP, P = 0.006 by 2‐tailed paired t‐tests; P < 10−6 by Fisher exact tests) but not in total aggregates from AD subjects (AD ≈ NC). Here, MAPT is linked to Alzheimer disease.