Several rats have been developed which manifest Alzheimer's disease with all the right symptoms: age-dependent cerebral amyloidosis that precedes tauopathy, gliosis, apoptotic loss of neurons in the cerebral cortex and hippocampus, and cognitive disturbance.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4496102/ [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3720142/