In major depressive disorder in people without MS, feedback inhibition of ACTH secretion by cortisol is compromised independently of an age effect on the hypothalamic–pituitary–adrenal axis function [22]; in MS, an association among mood disorders, dysfunction of the hypothalamic–pituitary–adrenal axis and cerebral inflammation (cerebrospinal fluid white blood cell counts and presence of Gd + lesions on MRI) have been reported, too [23]. This evidence concerns the gene POMC and mood disorder.