NPPB and Alzheimer disease: However, when examined within each group of subjects categorised by diagnosis, while not significant within the group of subjects with MCI (t = 0.927, p = 0.359), the difference in BNP-32 levels between the APOE4 non-carriers and the APOE4 carriers was significant at p < 0.05 in the healthy, control subjects (t(7694) = 2.285, p = 0.022) and at p < 0.1 in the group of subjects with probable AD (t(1495) = -1.961, p = 0.050).