INS and major depressive disorder: Several recent studies have investigated large numbers of peripheral molecules assessed in blood or urine, and were able to identify molecular signatures related to depression, which mainly comprised various markers involved in inflammation, insulin-related pathways and metalloproteinases.11, 12, 13, 14, 15, 16, 17, 18 It remains unclear, however, whether individuals with MDD in remission express similar protein profiles as individuals with current episodes, and whether altered protein levels could be ascribed to the presence of MDD or to antidepressant medication use.