In contrast, an increase in IAPPO-IgA levels was detected in +Aβ cases compared with −Aβ in Cohort II, but this increase was not found in the larger Cohort I. Hence, at a first glance, it appears as if an alteration in monomeric or oligomeric IAPP levels is not implicated in AD and neither is the availability of Igs against the different IAPP aggregation forms. Here, IAPP is linked to Alzheimer disease.