APP and Alzheimer disease: In APP/PS1 mice, a mouse AD model co-expressing mutated human APP with a Swedish mutation and mutated presenilin 1, overexpression of L1 using adeno-associated viruses results in a reduced Aβ plaque load and Aβ42/40 ratio, as well as milder hippocampal synapse loss and astrogliosis (Djogo et al., 2013).