Neuropsychological profile of chronic pain: implications for diagnosis and treatments

Chronic pain is a complex phenomenon with a multidimensional nature that involves both biology and psychology, as well as socio-cultural influences. While its primary function is to protect us from environmental and endogenous dangers, ensuring the survival of the species, when it becomes chronic it can be threatening to us, causing important physical and mental burden. In this complex phenomenon, psychology may play two important roles: the first is to provide a key to understanding the mechanisms beyond the chronification by exploring the various domains related to cognition, behaviours and psychological functions. The second role deals with non-invasive and non-pharmacological therapeutic approaches that, also by mean of psychology, can contribute to improving patients' conditions and the socio-economic management of the burden of chronic pain. In this framework, my research focused on both of these aspects. The first chapter will introduce the context of chronic pain, the specific characteristics of the different clinical conditions characterised by it, and provide a brief description of the main pathways connecting the central nervous system with the periphery, and vice versa. Furthermore, the neural correlates typical of chronic pain conditions will be briefly presented, and the main therapeutic approaches, currently known and applied in the broad field of chronic pain, will be illustrated. The second chapter will be focused on presenting the different experimental studies constituting my research activity. In particular, the first paragraph will present four research works focused on cognitive, behavioural and psychological functioning of three different populations affected by chronic pain, namely (i) small fibre neuropathy, a specific painful peripheral neuropathy, (ii) chronic primary pain conditions, and (iii) cluster headache. The results will address the issue of better characterizing their psychological functioning and will support the effective need for a clinical diagnostic framework that includes also cognitive, behavioural and psychological aspects of patients’ functioning. The final goal is to better target therapies, both pharmacological and non-pharmacological. Perfectly in line with the first aim, the second paragraph of chapter 2 will focus on two alternative therapeutical approaches for chronic pain, namely non-invasive brain stimulation techniques (NIBS) applied to chronic primary pain conditions, and mindfulness as a cognitive-behavioural approach applied to chronic migraine. In particular, the results of a systematic review on the therapeutic efficacy of NIBS on chronic primary pain will be presented, with specific considerations on the most effective protocols, on the outcomes mostly involved in literature that extend beyond just the intensity of pain, and on the short- and long-term effects, as well as the intriguing topic of the placebo effect. To conclude, the third and last chapter will elucidate the results obtained in light of the most recent literature findings, highlighting the limitations, innovative aspects, and those considerations that will drive research toward new objectives.