Most proteins were elevated in the MCI group, and effect sizes were largest for CHGA (β = 0.63 [SE 0.17] vs control subjects and 0.54 [0.23] vs AD), SCG-2 (β = 0.53 [SE 0.20] vs control subjects and 0.74 [SE 0.22] vs AD), NRXN-3 (β = 0.60 [SE 0.20] vs control subjects and β = 0.65 [SE 0.22] vs AD), and NPTX1 (β = 0.63 [SE 0.22] vs control subjects and β = 0.78 [SE 0.21] vs AD). Here, NPTX1 is linked to Alzheimer disease.