'Glucocorticoids, Cushing's syndrome and cellular senescence: a mechanistic link to metabolic ageing'.

Glucocorticoids are key regulators of immune, stress, and inflammatory responses, as well as of multiple metabolic pathways throughout life, and they play an anabolic role in tissue and organ development. Chronic glucocorticoid excess, whether due to endogenous Cushing's syndrome, long-term pharmacological treatment, or persistent stress, induces tissue-specific alterations that closely resemble those seen during physiological ageing. These shared changes include loss of tissue regenerative capacity, altered body composition, impaired glucose and lipid homeostasis, and increased cardiovascular and neuropsychiatric vulnerability. Emerging evidence indicates that glucocorticoid excess can promote cellular senescence, amplify pro-inflammatory signalling, and disrupt inter-organ communication, thereby accelerating a state of metabolic ageing. This review synthesises current clinical and experimental data linking glucocorticoid excess with cellular senescence in key metabolic organs and systems, including adipose tissue, skeletal muscle, liver, bone, the cardiovascular system, and the brain. Particular emphasis is placed on chronic neoplastic hypercortisolism as a human model, while also considering prolonged pharmacological glucocorticoid exposure and sustained stress as more prevalent, subclinical sources of hormonal overload. By integrating these lines of evidence, we outline the emerging concept of glucocorticoid-driven metabolic ageing and highlight potential mechanistic targets along the glucocorticoid axis and within senescence pathways. A better understanding of these mechanisms may inform strategies to prevent or mitigate age-related metabolic and cardiovascular complications in patients with Cushing's syndrome, in individuals exposed to long-term glucocorticoid therapy, and in the broader ageing population.