AD and Aβ+ MCI patients showed decreases in six plasma proteins, including JAM-B (d = − 0.23 in Aβ+ MCI; d = − 0.21 in AD; q < 0.001), brevican (d = − 0.2 in Aβ+ MCI; d = − 0.23 in AD; q < 0.05), thy-1 membrane glycoprotein (THY1; d = −-0.19 in Aβ+ MCI; d = − 0.13 in AD; q < 1 × 10− 5), RGMB (d = − 0.19 in Aβ+ MCI; d = − 0.12 in AD; q < 0.05), UNC5C (d = − 0.16 in Aβ+ MCI; d = − 0.11 in AD; q < 0.05), and TRAIL (d = − 0.16 in Aβ+ MCI; d = − 0.17 in AD; q < 0.05); see Fig. 1b and Table 3. Here, RGMB is linked to Alzheimer disease.