Apolipoprotein E genotype and in vivo amyloid burden in middle-aged Hispanics
Priya Palta1, Brady Rippon2, Christiane Reitz2
1From the Department of Medicine (P.P., B.R., G.S., F.C., J.A.L.), Vagelos College of Physicians and Surgeons, Department of Epidemiology (P.P., C.R., J.A.L.), Joseph P. Mailman School of Public Health, Department of Neurology (C.R., H.H., Q.R., A.M.B.), College of Physicians and Surgeons, Taub Institute for Research on Alzheimer's Disease and the Aging Brain (C.R., Q.R., A.M.B.), and Gertrude H. Sergievsky Center (C.R., Q.R., A.M.B.), Columbia University Irving Medical Center, New York; Research Division (J.T.), Hebrew Home in Riverdale, Bronx; Columbia University Stroud Center at New York State Psychiatric Center (J.T.); Department of Biomedical Engineering (Q.R.), Columbia University, New York; and Department of Neurology (H.M.), SUNY Downstate Medical Center, Brooklyn, NY. pp2464@cumc.columbia.edu.
Objective:
To examine in vivo amyloid burden in relation to APOEε4 genotype in middle-aged Hispanics. We hypothesize higher amyloid levels among APOE ε4 carriers vs APOE ε4 noncarriers.
Methods:
This is a cross-sectional study in a community-based sample of 249 middle-aged Hispanics in New York City who underwent a 3T brain MRI and PET with the amyloid radioligand 18F-florbetaben. APOE genotype was the primary exposure. The primary outcome was amyloid positivity. The secondary outcome was subthreshold amyloid levels examined as a continuous variable.
Results:
APOE ε4 carriers (n = 85) had a higher frequency (15.3%) of amyloid positivity compared to APOE ε4 noncarriers (n = 164, 1.8%). In the subthreshold group of amyloid-negative participants (n = 233), APOE ε4 carriers (n = 72) had a 0.02 (95% confidence interval [CI] 0.01-0.04) higher global brain amyloid standardized uptake value ratio (SUVR) compared to APOE ε4 noncarriers (n = 161). Compared to participants with the ε3/ε3 genotype, participants with ε4/ε4 had the highest frequency of amyloid positivity (28.6%), followed by those with ε3/ε4 (11%). Among amyloid-negative participants (n = 233), compared to participants with ε3/ε3 (n = 134), those with ε4/ε4 (n = 5) had a 0.12 (95% CI 0.07-0.17) higher global brain amyloid SUVR, and those with ε3/ε4 had a 0.02 higher SUVR (95% CI 0.003-0.04). Results were similar when a median split was used for elevated amyloid, when continuous amyloid SUVR was analyzed in all participants, and in nonparametric Mann-Whitney comparisons.
Conclusion:
Middle-aged Hispanic APOE ε4 carriers have higher in vivo brain amyloid burden compared with noncarriers, as reported in non-Hispanics.
