In view therefore of the chronic inflammation seen in the AD brain [28,29] and of the anti-inflammatory role of NA [30], Mateo et al 2006 [31] investigated interactions between the -1021T allele and SNPs of the regulatory regions of the pro-inflammatory cytokine genes, IL1A and IL6. They reported interactions between DBH -1021TT and both IL1A -889T (rs1800587) and IL6 -174GG (rs1800795). This evidence concerns the gene IL6 and Alzheimer disease.