Understanding the link between depression and pain.

Background and aims Patients seeking care for a pain problem very often also report symptoms of depression.In fact, depression is associated with the development of chronic pain as well as poor treatment results. Yet, the mechanisms by which depression and pain impact upon one another are not clear. This paper provides a critical review of the literature with the aim of shedding light on the relationship between pain and depression. Further, we introduce the Örebro Behavioral Emotion Regulation Model which may stimulate understanding in addition to research. Method Data bases (MedLine and PsychINFO) were searched as well as reference lists to locate relevant articles, especially previous reviews, published since 2000. We located 244 articles including 6 reviews. Results We found that while depression is strongly linked to pain, there is little understanding of how this link works or how it might be utilized in clinical settings. It is not clear whether one of the symptoms precedes the other, but when both are present prognosis is significantly affected. Clinicians often fail to assess both depression and pain resulting in probable "under" treatment of one or both problems. There is little evidence that treating the pain will result in the disappearance of the depression. Indeed, early improvements in depression are associated with overall treatment gains for patients with musculoskeletal pain. Therefore, treatment outcomes might be substantially enhanced by addressing both the pain and the depression. Moreover, directly addressing the depression early in treatment may be especially valuable. While pharmacological treatments of depression are often pursued for pain patients, the results for depression, pain and function are not impressive. Although there are effective cognitive-behavioral techniques for depression, these have not been properly evaluated in patients with co-morbid pain and depression. We found two likely mechanisms that can help to explain the link between depression and pain. First, catastrophizing plays a central role in models of both pain and depression and hence might form an important link between them. Second, emotion regulation is important in both depression and pain since they both can be viewed as significant emotional stressors. We offer a model which focuses on the recurrent nature of pain and depression. It hypothesizes that flare-ups trigger catastrophic worry which in turn strains the individual's emotion regulation system. Successful behavioral emotion regulation is said to result in coping while negative behavioral emotion regulation results in spiraling negative affect, pain and mood related disability and, in the long term, a consequent relapse. Implications Since both pain and depression are closely linked and are both involved in the development of long-term problems, it is important for clinicians to assess them as early as possible. Moreover, both symptoms should be monitored and addressed in treatment to maximize outcome results. Because pharmacological treatment has limited effects, cognitive-behavioral therapy is an alternative. Behavioral emotion regulation may be an important mechanism linking depression and pain. Conclusions It is concluded that pain and depression impact on each other and play an important role in the development and maintenance of chronic problems. Future studies of treatments for co-morbid depression and pain are urgently required. The purposed Örebro Behavioral Emotion Regulation Model provides much needed guidance for investigating the psychological mechanisms involved.