SYP and Alzheimer disease: Interestingly, however, when samples with additional pathologies not directly related to AD were excluded (n = 5; see Table S1 for cases excluded), a significant reduction in synaptophysin levels was detected (non-AD vs. AD (p < 0.05); Braak stage (p < 0.05, r = − 0.36, P.E. = ± 0.15); see Fig. S2), indicating a possible impact of secondary pathologies on the presynaptic compartment.