These mildly reactive astrocytes were in contrast to the severely reactive astrocytes observed in the GiD and APP/PS1-GiD mouse models of Alzheimer’s disease (AD)16,17, in which the severely reactive astrocytes exhibited MAO-B-dependent H2O2 production, iNOS, and Ki67, in addition to increased MAO-B and GABA. This evidence concerns the gene MKI67 and early-onset autosomal dominant Alzheimer disease.