TSPO and Insulin resistance: The findings on association between HOMA-IR and Aβ accumulation in the brain in APOE4/4 homozygotes are also in line with our previous findings which suggest that insulin resistance seems to be an additive risk factor for Aβ accumulation in APOE4 carriers.16 In the present study population, a correlation between [11C]PK11195 and [11C]PIB cortical composites was previously detected in only in APOE4/4 homozygotes.29 We did not find an association between hs-CRP or cholesterol values and TSPO binding or Aβ accumulation.