A study published in the journal Nature found that semaglutide, the active drug in the weight-loss injection Wegovy, significantly extended the lifespan of old female mice, according to Professor Rob Galloway, an emergency medicine doctor who wrote about the research.
Galloway said the findings reminded him of two of his own patients: one who died at 96 after a healthy life and only a brief final illness, and another who died at 73 after suffering from diabetes and dementia since their 60s, a contrast he said illustrated the difference between lifespan, how long someone lives, and healthspan, how long they remain well.
Researchers at the University of California, Berkeley, began treating the mice with the drug when the animals were 20 months old, an advanced age for mice, which normally live for around two to two and a half years.
Forty mice received daily semaglutide injections while 39 received salt-water injections for the rest of their lives, Galloway wrote. Mice given semaglutide lived an average of 92 days longer than the typical lifespan, an increase of about 12 per cent, even though treatment began only once the animals were already old.
Memory and physical performance
A separate group of old mice tested after three months of semaglutide treatment performed better in tests of memory, co-ordination and endurance than untreated mice, according to Galloway. In one memory test, treated mice found an escape hole in less than half the time taken by a placebo group, and they could run for almost three times as long before becoming exhausted.
Changes to gene activity
The drug also altered the activity of genes in the mice's liver cells, making genes linked to inflammation less active while genes involved in repairing DNA and clearing away damaged proteins became more active, Galloway wrote. Long-term inflammation and the build-up of cellular damage are among the reasons bodies deteriorate with age.
Semaglutide raised levels of NAD, or nicotinamide adenine dinucleotide, a compound that helps cells produce energy and repair damage but which declines with age. It also increased activity of sirtuin genes, sometimes called anti-ageing genes, which help cells use NAD to cope with stress and repair damage.
In a separate experiment, researchers compared semaglutide with a diet containing 24 per cent fewer calories. Both approaches led to mice losing similar amounts of weight and fat, but semaglutide produced better results on measures including memory and blood-sugar control, suggesting the drug may do more than simply cause weight loss.
Evidence from human trials
Galloway pointed to a 2023 trial published in the New England Journal of Medicine that followed 17,600 people who were overweight or obese with cardiovascular disease. Those given weekly semaglutide reduced their risk of a heart attack, stroke or death from cardiovascular disease by 20 per cent over three to four years, according to the trial.
A later analysis found much of that benefit could not be explained by weight loss alone, and suggested semaglutide may reduce inflammation, blood pressure, blood sugar and blood fats, though Galloway said researchers still do not know exactly why the drug protects the heart. Another major trial found semaglutide slowed kidney damage and reduced deaths among people with type 2 diabetes and kidney disease, he wrote.
A study published in May in the journal Nature Communications examined patients with HIV and excess abdominal fat, looking at DNA methylation, the chemical marks on DNA that indicate how quickly the body is ageing. Semaglutide slowed this process, Galloway wrote, even though HIV patients whose infection is well controlled can still have ongoing inflammation and signs of faster ageing.
Other drugs studied for longevity
Semaglutide is not the first drug to raise hopes of extending healthspan, according to Galloway. Metformin, a common diabetes drug, has been linked in some animal studies to a small increase in lifespan, though this has not been shown in humans. NMN, or nicotinamide mononucleotide, a substance the body makes naturally, delayed frailty in mice in early studies published in 2024 and kept some muscle genes behaving more like those of younger animals. Female mice in that research lived 8.5 per cent longer, though male mice did not.
Caution over healthy weight patients
Galloway said people who are otherwise healthy and of normal weight should not start taking Wegovy in the hope of living longer, since there have been no human trials showing the drug extends life or keeps people healthier for longer, and the drugs can carry side effects.
He said the animal data on semaglutide and ageing, combined with strong evidence of wider health benefits in humans and the drug's established safety record in treating obesity, suggested researchers could be "at the start of something very special." He said its potential as an anti-ageing drug needs serious investigation, adding that even healthy, slim people may end up taking it in future.
