Earlier studies found decreased immunoreactivities of both CREB and phosphorylated CREB (Yamada et al., 2003), decreased expression of CREB in postmortem brains of drug-free MDD-patients (Yuan et al., 2010) and decreased CREB protein expression in neutrophils of drug-free MDD patients (Ren et al., 2011). This evidence concerns the gene CREB1 and major depressive disorder.