PSEN1 and Alzheimer disease: The magnitude of synapse loss (∼25%) in APP/PS1 mice compared to age-matched wild-type littermates at the apical tuft (WT 3.11 ± 0.13 vs. AD 2.32 ± 0.12 puncta/μm, p = 1.0 × 10−4; Figures 6A–6D) was similar across these two ages.