The biological, social, and psychological relationship between depression and chronic pain.

Chronic pain and depression often occur simultaneously, may have common causal mechanisms, and may also influence each other. An understanding of their precise relationship would be useful for the prediction of response to treatment and for better pain management for chronic pain patients. A biopsychosocial model will be used in this review paper to elucidate the relationship between chronic pain and depression in biological, social, and psychological terms. Due to the enormous amount of information available, only a selective review of the most relevant literature was done. A critical analysis of the selected literature on the relationship between chronic pain and depression was performed to present an insight into this complex relationship.