Alzheimer’s disease induced by amyloid β1-42 peptide in rats showed a decrease in the levels of presynaptic protein synaptophysin (a marker of synaptic plasticity and integrity), Ki-67 (a nuclear protein associated with cellular proliferation) and doublecortin (a neuronal migration protein) in the brain. This evidence concerns the gene SYP and early-onset autosomal dominant Alzheimer disease.