The widespread presence of CGRP and its binding sites in the brain, eminently in limbic structures, indicates its potential involvement in a plethora of neurophysiological and neurobehavioral functions [40], like in depression [41, 42, 44], possibly in dementia [50], and in the pathophysiology of inflammatory and neuropathic pain [51–53]. This evidence concerns the gene CALCA and major depressive disorder.