A 2 year longitudinal study by Diniz et al. (2014) [121] presented a comparative study of the BDNF levels in three groups: (1) remitted depression with incident mild cognitive impairment (LLD + MCI); (2) remitted depression without cognitive decline (LLD + NCD); (3) control group (no depression and no cognitive impairment). This evidence concerns the gene BDNF and major depressive disorder.