Understanding How Chronic Pain Impacts Fall Risk and Mobility in Ageing

Background: Chronic pain is highly prevalent and is a leading contributor to disability, reduced mobility, cognitive decline, and increased fall risk with ageing. Despite its widespread impact, the mechanisms linking chronic pain to these adverse outcomes in ageing remain poorly understood. Existing treatment models often adopt a reductionist approach, overlooking the complex interplay between behavioural, psychosocial, and neurological factors. Aims and Objectives: This thesis examined the multifaceted pathways through which chronic pain influences mobility impairment and falls with ageing. Specifically, it aimed to: (1) quantify the association between pain and gait function, (2) test an integrated model of pain-related fall risk using large-scale epidemiological data, (3) explore the lived experience of pain in later life, and (4) investigate neurobiological mechanisms using advanced brain imaging. Methods: A multi-method design was used across four interlinked studies. First, a systematic review and meta-analysis synthesised evidence on the relationship between chronic pain and gait in people aged 60 years and over. Second, structural equation modelling of UK Biobank data in people aged 40 years and over evaluated direct and indirect pathways from pain to falls, mediated by depression, inflammation, physical activity, gait quality, and cognition. Third, a qualitative study with people aged 60 years and over living with chronic pain explored the emotional, social, and functional impact of pain in ageing. Fourth, a neuroimaging study examined the associations between brain integrity and fall risk factors in people aged 50 and over living with chronic pain. Findings were integrated within a biopsychosocial-neurocognitive framework. Results: The meta-analysis confirmed a consistent association between chronic pain and slower walking speed, identifying walking speed as an early marker of mobility decline. The UK Biobank analysis demonstrated that pain increased fall risk through both direct and indirect pathways involving depression, inflammation, walking speed, and gait quality. Qualitative findings revealed a mismatch between the lived experience of people aged 60 years and over and current pain assessment practices, highlighting the need for more person-centred approaches. Neuroimaging results revealed significant associations between grey matter volume, white matter integrity, and tissue conductivity in regions critical for balance, motor control, and cognition, including the cerebellum, thalamus, basal ganglia, and prefrontal cortex, as well as fall risk factors. Conclusion: This thesis presents converging evidence that chronic pain contributes to mobility decline through interconnected behavioural, psychological, and neurobiological mechanisms with ageing. The findings support the use of multidimensional assessment and holistic care strategies in both clinical and research settings. By integrating epidemiological, experiential, and neuroimaging evidence, this thesis offers a comprehensive framework for improving mobility, reducing fall risk, and addressing cognitive decline through multidimensional, targeted interventions for people living with chronic pain as they age.