Obesity drug extends mice’s lives and may slow ageing, study finds

Semaglutide, the active ingredient in the obesity drug Wegovy, helped older female mice live longer while improving their physical and cognitive abilities, according to a study from the University of California, Berkeley.

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These differences suggest that the drug may act through a biological pathway separate from calorie restriction.

The researchers gave the drug to 20-month-old female mice for three months. Because mice typically live a little over two years, the researchers compared that age with humans in their 60s, when ageing has begun to progress substantially. The treated mice explored more, balanced longer on a rotating rod, ran farther on a treadmill and solved mazes more quickly than mice given saline.

The difference also appeared in the animals’ lifespan. Mice given semaglutide had a median lifespan of 834 days, 92 days longer than the control group’s 742 days, an increase of about 12%. At the molecular level, the treatment eased several features associated with ageing, including chronic inflammatory gene activity, declining cellular regeneration, stem-cell depletion, mutation accumulation and mitochondrial dysfunction. Neural stem cells also multiplied in the hippocampus, and the production of new neurons increased.

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There is no guarantee that similar results will appear immediately in humans, but it is highly encouraging because it raises the possibility that GLP-1 drugs could extend healthy lifespan even in healthy people.

The Berkeley team compared semaglutide with a diet that cut calories by 24%, matching the reduction the treated mice achieved on their own. Both groups showed similar results across many physiological measures, but the semaglutide mice performed above baseline in exploration, spatial memory and blood-sugar control. The calorie-restricted mice generally maintained baseline performance. They also showed lower oxygen consumption and energy expenditure during the day, while the semaglutide mice maintained a normal metabolic rate.

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This study suggests that the cardiovascular, kidney and liver protective effects of GLP-1 drugs may reflect regulation of the ageing rate rather than simply being a byproduct of weight loss.

Professor Danika Chen said the results suggested that semaglutide may act through a biological pathway distinct from calorie restriction, without the physical stress of hunger. She cautioned that similar effects in humans are not guaranteed. Experts noted that the study used only one strain of female mice, and that the drug can reduce muscle mass in humans. Kyung Hee University professor Lee Sang-yeol warned that the findings should not justify giving the drug to thin older people at risk of sarcopenia. Nature reported that clinical trials are examining the drug’s effects on ageing, but no completed trial has yet evaluated it in healthy older adults.

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The drug should not be used as evidence for thin older people at high risk of sarcopenia to take it in order to slow ageing.