Chronic Pain, Dopamine and Depression: Insights from Research on Fibromyalgia

Abstract

There have been several indications that pain and reward are partly mediated by similar neural pathways in the central nervous system, and that these common pathways are related to both the dopamine (DA) and the opioid systems. Several studies have demonstrated the analgesic effects of rewarding stimuli or activities on positive affective states. On the other hand, chronic pain was shown to impair several aspects of reward processing by possibly altering pain-reward interac-tions. However, the precise mechanisms of the mutual pain-reward interaction are unclear and few studies have investigated the influence of pain on rewards and vice versa in humans. Therefore, we aim to summarize recent findings on the neuroana-tomical and molecular chances associated with chronic pain conditions, particularly fibromyalgia syndrome (FMS) with a focus on the dopamine system. Recent findings on the mechanisms involved in the alterations of the brain reward circuit in chronic pain and FMS as well as the role of DA in the pathophysiology of FMS and other chronic pain conditions will be discussed. Furthermore, we aim to discuss the interplay between the dopaminergic reward system and depression in chronic pain, as the prevalence of co-morbid depression in chronic pain is quite high.