Many faces of depression in patients with chronic pain.

Depression is commonly associated with chronic pain patients. How common is it and what are its manifestations? Research findings are unclear. Besides, depression is defined by some as a syndrome and by others as an affect or symptom. This leads to further confusion. This paper attempts to answer those questions by a selected review of the pertinent literature and case examples to demonstrate reactive, clinical and masked depression and also depression as an affect or symptom. Some of the treatment issues are considered.