Immunohistochemical analysis of myelin basic protein (MBP) in the stratum radiatum of CA1 showed that PS19-E4 mice had a significantly lower coverage area of MBP relative to PS19-E3 mice (Figures S1F and S1G), indicating that APOE4 leads to hippocampal myelin deficits in the context of tauopathy. Here, APOE is linked to tauopathy.