Injection of Aβ peptide into the brain of wild type mice has also been used to model AD, and has been reported to lengthen period and blunt clock gene rhythms in the SCN (Navigatore-Fonzo et al., 2017), and to alter expression patterns of Apoe and other mRNAs in the hippocampus (Wang et al., 2016), though this model is not widely used. Here, APOE is linked to Alzheimer disease.