PSEN1 and early-onset autosomal dominant Alzheimer disease: This report is part of a continuous series of studies that focus on quantitative analysis, using RT-PCR protocol, selected genes associated with Alzheimer’s disease in various rat brain structures, such as α-secretase, β-secretase, presenilin 1 and 2, amyloid protein precursor, and tau protein to assess the selective susceptibility to ischemia of pyramidal neurons in the CA3 region of the hippocampus during development of neurodegeneration and dementia after ischemia.