In MCI patients (mean 1.5% CTLA-4 + CD4 + /CD4 + ; p = 0.0392; Fig. 2c) and in patients with moderate AD (mean 1.4% CTLA-4 + CD4 + /CD4 + ; p = 0.0187), the expression of CTLA-4 by CD4 + T cells was increased compared to non-demented controls (average 1% CTLA-4 + CD4 + /CD4 +). This evidence concerns the gene CTLA4 and Alzheimer disease.