Although aged NHPs with existing AD-like pathology have been successfully vaccinated against Aβ [32], few aged NHPs without AD pathology have been evaluated, showing no differences in hippocampal levels of soluble and insoluble Aβ or cytokines (TNF-α, IL-1α, IL-1β) between Aβ- and control-immunized animals [42]. This evidence concerns the gene IL1B and Alzheimer disease.