PSEN1 and Alzheimer disease: The UKUR25 model with human APP 751 and PS1 transgenes and the UKUR28 model with mutated human APP 751 transgene were both reported to display intracellular accumulation of Aβ peptides in the cerebral cortex and hippocampus at the age of 6 months corresponding to the “pre-plaque” stage in AD [92].