PSEN1 and early-onset autosomal dominant Alzheimer disease: Perhaps the proof of concept of the anti-Aβ approach will come from the Alzheimer’s Prevention Initiative Autosomal-Dominant Alzheimer’s Disease Trial, where anti-Aβ antibody is being administered pre-symptomatically to Columbian family carrying the PSEN1 E280A autosomal-dominant mutation that causes early-onset Alzheimer’s disease64.