A study in a Drosophila model of Alzheimer’s disease (AD) in which the major human peptide associated with AD pathology, amyloid-beta 42 (Aβ42), was overexpressed in photoreceptor cells in the eye showed that components of the Toll pathway mediate Aβ42-induced neurotoxicity [69]. Here, TLR4 is linked to Alzheimer disease.