In contrast, CD8+ HLA-DR+ T-cell proportions in the PB were elevated in ALS patients compared with PPMS (0.88%, IQR 0.41–1.40, P = 0.002) patients, whereas there was no difference compared with dementia patients (1.49%, IQR 1.26–2.27, P = 0.999). This evidence concerns the gene CD8A and dementia.