In this framework, it should be also mentioned that even increased serum or plasma BDNF levels have been obtained in mood disorder patients under peculiar states such as a high cytokine IL-1β production, in bipolar disorder-II vs. subthreshold bipolar patients or in pain disturbances and in adaptive disorders [42,65,78,80,89,90,91,92]. This evidence concerns the gene BDNF and bipolar II disorder.