CD14+CD16− monocytes in PB and CD8+ HLA-DR+ T-cell frequencies in the CSF did not differ between those cohorts (P = 0.050/0.999, P = 0.999/0.651), whereas the intrathecal level of T-cell activation was increased for CD4+ T cells compared with dementia (8.65%, IQR 5.58–11.55, P = 0.035) but not with PPMS (8.79%, IQR 5.58–12.86, P = 0.110). This evidence concerns the gene CD8A and dementia.