International Journal of Review Clinical Rheumatology Thiagarajah, Guymer, Leech & Littlejohn The relationship between fibromyalgia, stress & depression 9 Review The relationship between fibromyalgia, stress and depression Int. J. Clin. Rheumatol. Fibromyalgia is noted for its association with both psychological stress and depression. Angeline S Thiagarajah1, However, the precise nature of these relationships remains contentious, as indicated Emma K Guymer1,2, Michelle by a large body of conflicting literature. Inconsistencies regarding the nature of Leech1,2 & Geoffrey O ,1,2 stress in fibromyalgia are related to the poor characterization of biological stress Littlejohn* 1Department of Medicine, Monash systems in the different presentations of fibromyalgia. Similarly, conflicting literature University, Melbourne, Australia regarding depression and fibromyalgia is likely due to the heterogeneous nature of 2Department of Rheumatology, Monash both fibromyalgia and depression. Emerging evidence indicates that fibromyalgia and Health, Melbourne, Australia depression are both syndromes, which affects the way in which each disorder should *Author for correspondence: be considered. In this review, the nature of stress and depression in the context of [email protected] fibromyalgia will be discussed. Keywords: depression • diathesis–stress • fibromyalgia • HPA axis • stress Medscape: Continuing Medical Education Online This activity has been planned and implemented in accordance with the Essential Areas andpolicies of the Accreditation Council for Continuing Medical Education through the joint providership of Medscape, LLC and Future Medicine Ltd. Medscape, LLC is accredited by the ACCME to provide continuing medical education for physicians. 10.2217/IJR.14.30 Medscape, LLC designates this Journal-based CME activity for a maximum of 1.0 AMAPRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity. All other clinicians completing this activity will be issued a certificate of participation. 4 To participate in this journal CME activity: (1) review the learning objectives and author disclosures; (2) study the education content; (3) take the post-test with a 75% minimum passing score and complete the evaluation at www.medscape.org/journal/ 2014 ijcr; (4) view/print certificate. RELEASE DATE: 15 October 2014; EXPIRATION DATE: 15 October 2015 LEARNING OBJECTIVES Upon completion of this activity, participants will be able to: • Distinguish events that might promote fibromyalgia • Analyze psychological traits associated with the diagnosis of fibromyalgia • Assess the effects of stress, fibromyalgia, and depression on the hypothalamic–pituitary– adrenal axis • Evaluate the relationship between depression and fibromyalgia part of 10.2217/IJR.14.30 © 2014 Future Medicine Ltd Int. J. Clin. Rheumatol. (2014) 9(4), 371–384 ISSN 1758-4272 371 Review Thiagarajah, Guymer, Leech & Littlejohn Financial & competing interests disclosure E ditor: Laura Dormer, Senior Manager – Commissioning & Journal Development, Future Science Group. Disclosure: Laura Dormer has disclosed no relevant financial relationships. CME author: Charles P Vega, MD, Associate Professor and Residency Director, Department of Family Medicine, University of California, Irvine, CA, USA. Disclosure: Charles P Vega, MD, has disclosed the following financial relationships: served as an advisor or consultant for McNeil Pharmaceuticals Authors & credentials: Angeline S Thiagarajah, BMedSc (Hons), Department of Medicine, Monash University, Melbourne, Australia Disclosure: Angeline S Thiagarajah has disclosed no relevant financial relationships. Emma K Guymer, MBBS, FRACP, Department of Medicine, Monash University, Melbourne, Australia and Department of Rheumatology, Monash Health, Melbourne, Australia Disclosure: Emma K Guymer has disclosed no relevant financial relationships. Michelle Leech, MBBS, PhD, FRACP, Department of Medicine, Monash University, Melbourne, Australia and Department of Rheumatology, Monash Health, Melbourne, Australia Disclosure: Michelle Leech has disclosed no relevant financial relationships. Geoffrey O Littlejohn, MBBS (Hons), MD, MPH, FRACP, FRCP (Edin), Department of Medicine, Monash University, Melbourne, Australia and Department of Rheumatology, Monash Health, Melbourne, Australia Disclosure: Geoffrey O Littlejohn has disclosed no relevant financial relationships. No writing assistance was utilized in the production of this manuscript. Fibromyalgia is a common chronic pain syndrome, The HPA axis is itself quintessentially associated which affects 2–4% of people worldwide [1] . Women with stress, and emotional stressors result in the direct with fibromyalgia outnumber men by a ninefold fac- activation of the HPA axis [5]. The function of the HPA tor [2]. Chronic widespread pain (CWP) is the cardinal axis and its effects on the hippocampus also involves symptom of fibromyalgia, and associated symptoms memory and learning, key to adaptability in stressful defining the phenotype include sleep disturbance, situations [7,8]. The reciprocal connection between the fatigue and cognitive dysfunction. Psychological HPA axis and the locus coeruleus means that activa- experiences of anxiety and affective dysfunction are tion of the physical stress response necessarily involves common [3]. the emotional stress response, and vice versa [6]. Given the abundance of psychological phenomena Both the locus coeruleus and the HPA axis have contained within the associated symptoms of fibromy- additional bidirectional projections to the amygdala algia it is expected that it is commonly associated with [6]. The amygdala is responsible for the processing of stress. The strength of this relationship is such that stimuli that may cause fear, which links it to the notion fibromyalgia has been described as a ‘stress-related ill- of stress [6]. Together, the locus coeruleus, HPA axis ness’ [3]. However, in order to contextualize the impor- and the amygdala have a conceptually triangular rela- tance of stress in the pathogenesis of fibromyalgia, the tionship. This constitutes the body’s core mechanism nature of stress must first be discussed. for a response to stress which is in turn modulated by the prefrontal cortex (Figure 1) [6]. What is stress? Chronic stress has been associated with both HPA Although the term ‘stress’ is ubiquitous in both clinical axis hyperactivity and HPA axis hypoactivity [12] . and lay vocabularies, the concept of stress is difficult There are various theories as to the reasons for this to define. Broadly, stress may be conceptualized as any discrepancy, one being that HPA axis activity depends challenge that disrupts the body’s natural homeostatic on a person’s response to stress. A meta-analysis asso- mechanisms [4]. This challenge may come in the form ciated HPA axis hyperactivity with subjective distress of a physical stressor, or a psychological stressor. responses, whereas HPA axis hypoactivity was more Physical stressors, including infections and tissue closely associated with stressed people who went on to damage, result in the activation of the locus coeruleus develop post-traumatic stress disorder [12] . Alternatively, in the rostral pons [5]. The locus coeruleus, involved the association of stress and HPA axis hypoactivity in in the modulation of physiological stress responses, conditions such as fibromyalgia or rheumatoid arthritis arousal and sleep, also projects to the hypothalamus, has been used to explain the variation in studies regard- connecting it to the hypothalamic–pituitary–adrenal ing the nature of the HPA axis in chronic stress states (HPA) axis [6]. [12,13]. Although the reason for the different associa- 372 Int. J. Clin. Rheumatol. (2014) 9(4) future science group The relationship between fibromyalgia, stress & depression Review Psychological stress Prefrontal cortex Serotonergic HPA axis system Raphe Amygdala nuclei Locus Noradrenergic coeruleus system Physical stress Figure 1. Biological systems and neurological regions related to stress and pain in fibromyalgia. Connections between elements in this model are bidirectional. HPA: Hypothalamic–pituitary–adrenal. Data taken from [6,9–11]. tions of the HPA axis with stress remains debatable, it is nuclei are associated with serotonergic pain pathways clear that chronic stress can be viewed a heterogeneous [11] . Again, this system is influenced by its connections construct, as it may be associated with either HPA axis to the prefrontal cortex, suggesting higher-level neural hyperactivity or HPA axis hypoactivity. control over these systems (Figure 1) [11] . All of these biological systems and neurological How does stress relate to pain & regions have been associated with fibromyalgia. Vari- fibromyalgia? ous elements of the HPA axis have been observed to be The stress–response system outlined above does not abnormal in fibromyalgia (Table 1) [14–16] . exist in isolation from other neural mechanisms. As The inconsistent association of the HPA axis with a noradrenergic neuron cluster, the locus coeruleus fibromyalgia presents a similar picture to the varied is associated with the function of noradrenergic pain relationship between stress and the HPA axis, and control pathways, which in turn are associated with again, could reflect the heterogeneous nature of fibro- descending serotonergic pain pathways [9,10]. The myalgia. However, many studies concur that HPA axis additional association of the amygdala