Comorbidity of Depression and Pain: a review of shared contributing mechanisms

Pain and depression are two major health issues that we are currently facing. Chronic pain is the main reason that people seek medical care; and numerous people commit suicide each year because of depression. These two pathological conditions often coexist. Chronic pain patients are more likely to develop major depressive symptoms, while depressed patients reported more pain symptoms than normal healthy population. Understanding the common mechanisms associated with depression and pain is important for developing the effective strategy to treat this comorbidity. In this review, the potential mechanisms that contribute to both depression and pain are discussed from four perspectives, the morphological changes in the brain, monoamine deficiency, brain-derived neurotrophic factor (BDNF) reduction in the hippocampus, and the hypothalamic-pituitary-adrenocortical (HPA) axis dysfunction.