BACE1 and early-onset autosomal dominant Alzheimer disease: Since synaptic activity regulates BACE1 trafficking and APP processing [19-21] it is possible that synaptic activity impairment observed in Alzheimer’s disease could affect BACE1 transcytosis in a manner that promotes its accumulation in dystrophic neurites, thus contributing to local Aβ production near the presynaptic terminals.