Abstract/Summary

Pain and emotional dysregulation are prevalent conditions in our society that impact daily functioning and quality of life. Often, these conditions occur comorbidly and exacerbate each other. Underlying neural and behavioural mechanisms involved in processing pain and emotion overlap, which formed the basis of an ongoing debate on the comparability and phenomenology of pain as a result of nociception opposed to social or emotional distress in the absence of nociceptive input. Pain modulated by negative emotion is increased, while positive emotions have been shown to facilitate pain reduction. Evidently, pain and emotion are strongly entwined, and the primary aim of this Ph.D. project was to further the understanding of the bidirectional modulatory influences of emotion and pain. In an attempt to reduce ambiguity around the use of pain scales to express emotional distress, Chapter 2 presents findings of two studies on reported pain responses following social rejection in the absence of nociceptive stimulation. Although half of the participants reported pain despite the option of alternative distress scales, one individual described the experience as an injury. Findings suggest that pain and emotion appear to overlap particularly on a linguistic level but emphasise the need to distinguish between experiences, taking into consideration their respective phenomenology (“physical pain” vs. “emotional pain”) to avoid ambiguity around self-reported pan in clinical and experimental settings. One way that this could be done is by following up with individuals to determine whether self-reports were due to “physical” or “emotional” pain. Chapters 3 and 4 discuss the effects of treatment approaches to reduce pain and negative emotions. In Chapter 3, a lab-based experiment used pain- and affect-focused cognitive reappraisal to reduce self-reported pain and distress and tested the effectiveness of cognitive intervention on secondary hyperalgesia (SH), a central pain process. Findings demonstrated that cognitive reappraisal successfully reduced pain and negative affect, as well as SH, regardless of its focus. These findings suggest that a psychological intervention focusing on either reappraising pain or emotion may be beneficial, specifically in comorbid clinical populations. Future research should further investigate the specificity of cognitive top-down modulation of central pain processes through reappraisal or general cognitive effort. A clinically depressed population with comorbid chronic pain received antidepressant treatment, as described in Chapter 4. Individuals whose depression improved with treatment, reported reduced pain intensity and interference. These findings suggest that pharmacological treatment aimed to reduce affective symptoms can positively modulate co-occurring pain when mood improves. Taken together, the findings confirm the bidirectional relationship of pain and negative affect and suggest that the modulation of emotions through cognitive and pharmacological intervention can reduce pain and its impairment on functioning. The work of this thesis contributes to the understanding of mechanisms underlying the overlap between pain and emotion and offers several suggestions for future mechanistic and clinical research to further investigate cognitive modulation of central pain processes and inform treatment of comorbid pain and affective pathologies.