Psychological and perceptual processes in persistent physical symptoms

Persistent physical symptoms encompass a constellation of non-specific symptoms such as (and not limited too) somatic pain, constipation, fatigue, dizziness, sensorimotor dysfunction, or a combination of. These symptoms are chronic, burdensome, and expressed without a well-defined organic cause. Research has shown behavioural, cognitive, affective, and perceptual processes are relevant in the expression and maintenance on these symptoms. Thus, across seven studies, this thesis aimed to (1) investigate behavioural processes leading to healthcare seeking, and determine their universal or uniqueness to persistent physical symptoms, (2) determine cognitive and affective processes related to the symptom burden and treatment of persistent physical symptoms, and similarly determine their uniqueness or commonality to symptoms with organic causes and (3) present experimental evidence for an emerging model for symptom perception which may open new avenues for understanding neurobiological processes leading to persistent physical symptoms. Results showed salient mind-body relationships when predicting behavioural outcomes, specifically healthcare seeking in individuals with persistent physical symptoms. Importantly, the magnitude of these mind-body relationships were similar to those without persistent physical symptoms. Investigations into the relationships between cognitive and affective components with physical symptom burden and response to subsequent psychological treatment highlighted substantial commonality with physical symptoms of well-defined organic causes. Finally, in support of a contemporary model of symptom expression in persistent physical symptoms, an experimental paradigm, known as the force-matching task, was developed, evaluated, and tested in individuals with persistent physical symptoms. These results highlighted subtle experimental differences in those with persistent physical symptoms compared to healthy controls, suggesting an association between altered perceptual processes and physical symptom expression. This thesis brought together distinct methodologies and areas of research to provide a comprehensive understanding of persistent physical symptoms and highlights central processes underlying symptom perception. The work presented in this thesis opens new avenues for treating neuro-psycho-behavioural processes related to persistent physical symptoms.