For example, pairwise interhemispheric connectivity was reduced between the hippocampus and cerebellum of apolipoprotein E APOE4 carrier (a genetic risk factor for Alzheimer disease) compared with APOE3 mice.34 As overall structural connectivity appeared more or less unchanged in the hypoperfused mice, it was not surprising that there were no differences between sham and hypoperfused mice in terms of network characteristics. This evidence concerns the gene APOE and early-onset autosomal dominant Alzheimer disease.