It has been reported that molecular mechanisms and pathways that underlie the pathogenesis of depression (i.e., impairment in the signaling of some neurotrophins such as Transforming-Growth-Factor-β1 and Brain-derived-neurotrophic-factor) are also involved in the pathogenesis of AD [114], [115], thus the omega-3 PUFA supplementation may not be the optimal pharmacological approach for this specific group of patients [116]–[118]. This evidence concerns the gene BDNF and depressive disorder.