MAPT and Alzheimer disease: We also observed expected differences in APOE ε4 frequency among biomarker groups consistent with previous work in both cognitively normal [3] and MCI [4] cohorts, suggesting the ε4 allele frequency is lower in participants with SNAP compared to amyloidosis (Aβ+/ND- or Aβ+/ND+[2, 30] The APOE ε4 allele is thought to promote risk for AD through an amyloid rather than tau pathway [31], and the present results suggest that APOE ε4 does not exert a major effect in the pathophysiology of neurodegeneration in SNAP.