Correlations between APOE4 status and regional amyloid and tau burdens in cognitively normal older individuals

Abstract

AbstractBackgroundThe correlations between apolipoprotein epsilon 4 (APOE4) status and regional Alzheimer’s disease–related biomarkers in cognitively normal elderly are not fully understood. Our cross‐sectional study compared clinical characteristics, amyloid/tau burden, and cortical thickness according to APOE4 carrier status to assess correlations between APOE4 and regional biomarker burdens.MethodWe analyzed 185 cognitively normal participants from the ADNI 3 cohort study. Participants aged 55‐90 with normal cognitive function were eligible. We divided participants into Aß+ APOE4 carriers (group 1, n = 27), Aß+ APOE4 non‐carriers (group 2, n = 29), and Aß‐ normal controls regardless of APOE4 carrier status (group 0, n = 129). We compared clinical characteristics, cerebrospinal fluid (CSF) amyloid β42 & phosphorylated tau, florbetapir positron emission tomography (PET), flortaucipir PET, cortical thickness, and cognitive scores among the 3 groups. Quantitative imaging analyses were performed using the standardized uptake value ratio (SUVR). We additionally assessed correlations between APOE4 carrier status and imaging biomarkers.ResultThe baseline characteristics except age were similar among the groups. The participants in group 2 were oldest. The regional amyloid/tau SUVRs did not differ between groups 1 and 2, but the amyloid/tau SUVRs in most regions were numerically higher in group 1 than group 2 after adjusting for age difference. The regional amyloid and tau SUVRs in the younger (<70) group were higher in group 1 than group 2. APOE4 carrier status showed significant association with amyloid burden in diffuse cortical areas after adjustment for age and sex, but it was not associated with regional tau burden or cortical thickness.ConclusionWe identified that cognitively normal APOE4 carriers showed similar but numerically greater amyloid and tau burdens than did APOE4 non‐carriers after adjusting for age. APOE4 carrier status might be more highly associated with amyloid deposition than with other AD‐related biomarkers such as tau or cortical thickness, especially in the younger group below 70.