Pain and depression: The janus factor of human suffering

The Cartesian dualism between the res extensa (material substance) and the res cogitans (thinking thing) has governed biological research and medical science for centuries. More than in other contest, research on pain and psychiatry has "suffered" the Cartesian dualism, having been respectively relegated over time to the body and to the soul or mind. In this context, mood disorders represent a paradigm but also a framework for an integrated view which allows to improve the knowledge and management of pain. Based on the relevance of the body's perception, a new concept of mind appears under construction as the result of integrated efforts between neuroscientists and clinicians. In this chapter we report the psychoanalytic point of view, which overcomes the concept of body and mind, indicating the pain as a psychical state expressed through localized bodily sensation, rather than as a concept in itself, offering a further interpretation of pain and its attributes. In addition, the historical and recent research findings and clinical evidence which have contributed to disclose the association of mood disorders and pain, with particular focus on depression, medically unexplained pain, brain changes in pain and the role of antidepressants as "analgesic" in the pain symptom management in neurological and psychiatric disorders.