Depression in people with pain: There is still work to do: Commentary on ‘Understanding the link between depression and pain’

Abstract

Depressionhas longbeen recognized as a commonco-morbidity mongst people with chronic pain. Estimates of the prevalence f depression in patients attending pain services range from 1.5% o 100% [1] but most estimates lie between 30 and 50%, partly ependent upon criteria for depression [2,3]. The nature of their elationship has also been the subject of extensive debate, theoetical constructions, and research. Some researchers have argued or causal relationships between the two, but disagreed over the irection of causality (see reviews by Romano and Turner [2] and ishbain et al. [4]). Others have argued the two constructs are indisinguishable and that chronic pain is really a form of depression or ‘masked’ depression [5]. Two authoritative reviews published over 14 years ago conluded the weight of evidence indicated that depression is more ikely to follow the onset of chronic pain rather than the reverse 2,4]. However, studies published in the last 10–12 years have sugested the relationshipmay bemore one of interaction rather than inear causation [1]. One emerging source of evidence that was arely available until relatively recently has come from primary are settings involving patients presenting with acute pain, often ssociated with workplace or motor vehicle injuries (see review y Chou and Shekelle [6]). This has provided an opportunity for rospective or longitudinal studies in which baseline characterisics, such as depression, can be related to subsequent chronic pain nd associateddisability. As a resultwehave been able to gainmore omprehensive insights into these evolving problems and the role f mood disorders like depression in these processes; something hich is not possible in cross sectional studies of patients attendng chronic pain services – the source of much of the early research nto pain and depression. Further insights into the relationship between pain and depresion have been gleaned from community-based epidemiological tudies (i.e., not based on people attending clinics). The large nternational epidemiological study by Demyttenaere et al. [7] for xample, found strong associations between chronic pain condiions and mental disorders, especially depression. Such studies ndicate that patients with chronic pain conditions are at higher isk of also having variousmental disorders. The implication is that