Biochemical mechanisms driving the clinical features of frailty

Introduction

Frailty is a common syndrome characterised by reduced physiological reserve and increased vulnerability to stressors presenting with hallmark features of sarcopenia, fatigue, neurodegeneration and immune dysregulation. This may result in adverse outcomes such as falls, disability and hospitalisation. Although frailty is routinely identified phenotypically, the biological mechanisms underpinning its clinical features are not always integrated into clinical understanding. This poster aims to explore the roles of these pathways in the development of frailty and to illustrate how these processes contribute to its clinical manifestations.

Methods

A narrative review of literature from the last 20 years was undertaken using peer-reviewed articles identified from PubMed, Embase, and Cochrane library. Evidence relating to immune system remodelling with age, chronic low-grade inflammation, oxidative stress and mitochondrial dysfunction was compiled. Systematic reviews and meta-analyses linking these biological processes to recognised clinical features of frailty were prioritised to develop a clinically translatable picture.

Results

Immune remodelling with age results in a chronic increase of inflammatory cytokines. This chronic inflammatory state is amplified by oxidative stress, leading to mitochondrial dysfunction, impaired ATP production and reduced ability to regenerate. These converging pathways reduce physiological resilience across the whole body. Sarcopenia develops through oxidative damage to muscle fibres, suppression of anabolic signalling pathways and impaired muscle regeneration. Neurodegeneration is promoted by microglial activation and reduced clearance of neurotoxins, while mitochondrial damage contributes to fatigue. This immune remodelling increases susceptibility to infection and impairs recovery from acute stressors.

Conclusion

Frailty is driven by biological failures that underpin its presentation rather than being an inevitable consequence of ageing. Inflammageing and oxidative stress represent crucial processes contributing to reduced physiological reserves. Improved understanding of these mechanisms may support implementing focused interventions, including resistance exercise and novel biologic therapies to preserve function, and improve outcomes for older adults living with frailty.