A 30% to 60% co-occurrence rate of major depressive disorder (MDD) and chronic pain has been reported. Recent developments in neuroscience and psycho-immunology point to the fact that comorbid pain and depression may be driven by overlapping pathophysiological processes in the brain and the body. In this first of a 2-part article from Current Psychiatry, the authors review the scientific understanding of these shared processes and demonstrate how recent advances in epidemiology, phenomenology, and etiology of chronic pain and MDD provide important clues for more effective diagnosis. For more, go to: http://www.currentpsychiatry.com/the-publication/issue-single-view/chronic-pain-and-depression-understanding-2-culprits-in-common/2ec40661fbe6eed587a2ff8b6590399b.html.