title: Chronic pain: an addiction.
abstract: Chronic pain is distinguished from persistent pain and it is proposed that chronic pain involves addiction to the endogenous opioid system. Even when the organic lesions responsible for pain are removed, chronic pain can be maintained as an internal state preventing the withdrawal or abstinence syndrome associated with endorphins and enkephalins.
mesh_terms: D002908:Chronic Disease; D004723:Endorphins / Q000502:physiology; D004745:Enkephalins / Q000502:physiology; D006801:Humans; D008960:Models, Psychological; D010146:Pain / Q000503:physiopathology / Q000523:psychology*
chemical_list: D004723:Endorphins; D004745:Enkephalins