APOE and Alzheimer disease: Further investigations into the oxidative marker revealed levels of TBARS were 1.56 ± 0.72, 1.70 ± 0.73, 1.86 ± 0.71 in the three individual APOE4 groups of the AD cohort, and 1.48 ± 0.84, 1.74 ± 0.94, 1.80 ± 0.79 in the individual APOE4 groups of the non-AD cohort (Table 2).