This is illustrated by studies showing that IAPP deposition impairs brain function regardless of Aβ-42 pathology (Srodulski et al., 2014) and that the brain of AD patients can also have IAPP deposits, alone or in the presence of Aβ-42 (Fawver et al., 2014), even if clinical signs of diabetes are absent (Jackson et al., 2013; Oskarsson et al., 2015). This evidence concerns the gene IAPP and Alzheimer disease.