We found that overexpression of AD-associated human Tau 0N4R caused the greatest degeneration of the photoreceptors causing a reduction of ∼60% in eye size compared to control, with Aβ42 also being neurotoxic decreasing the eye by ∼50%, while overexpression of fly mnb caused more modest cell loss reducing the eye size by ∼25%. Here, DYRK1A is linked to Alzheimer disease.