APP and Alzheimer disease: Altogether, these data indicate that rod photoreceptors of TG APP/PS1 present an enhanced response, which is already detectable at the low intensity of the light flash during pre-symptomatic stage in TG APP/PS1 mice, whilst for the higher light intensities, this enhancement is detectable only at the mid-stage of AD-like pathology (i.e., 9–12 months).