At the Longevity Summit Dublin 2024, Dr. Holly Brown-Borg, a leading researcher in the biology of ageing, presented her work on growth hormone and its effects on longevity. Her talk emphasized the complex relationship between GH and ageing, showing that reduced GH can extend lifespan and healthspan in animal models. She discussed the evolutionary trade-offs between growth and longevity, using insights from studies on mice with altered GH signalling. Brown-Borg's research challenges the notion that growth hormone promotes anti-ageing, presenting compelling evidence that it may actually accelerate ageing and associated diseases​.

Key Points:

• Growth Hormone and Ageing: Holly Brown-Borg focused on the role of somatotropic signalling, particularly growth hormone (GH), in ageing. Research shows that while GH supports tissue growth and metabolism, its decline with age may be beneficial for longevity.
• Growth Hormone's Dual Role: GH can have contradictory effects on ageing: while some believe it can delay ageing by preserving muscle mass and reducing fat, evidence suggests it may accelerate ageing by promoting diseases like diabetes and cancer.
• Reduced GH and Extended Lifespan: Studies using mouse models with reduced growth hormone signalling (like Ames dwarf mice) showed a 49-68% increase in lifespan. These mice are resistant to stress and maintain better metabolic health compared to normal mice.
• Methionine Restriction: The reduction of methionine in the diet, known to extend lifespan in other models, has little effect on GH-deficient mice, suggesting GH influences how organisms respond to dietary interventions.
• GH and Healthspan: Reduced GH levels seem to protect against common age-related diseases, like cancer and diabetes, and even cognitive decline related to Alzheimer's disease. This highlights a key trade-off between growth and longevity.
• Muscle Function and Frailty: Even though GH-deficient mice are smaller and have fewer muscle fibres, they maintain higher grip strength and experience less age-related frailty compared to their normal counterparts.