CSF samples from 16 AD patients grouped according to CSF t-tau levels, using as cut-off value the median of CSF tau levels of all our sample (680 pg/ml), and APOE genotype, resulting in 4 groups (each one consisting of four subjects), namely APOE3 low t-tau levels (LTE3), APOE3 high t-tau levels (HTE3), APOE4 low t-tau levels (LTE4) and APOE4 high t-tau levels (HTE4). Here, APOE is linked to Alzheimer disease.