One of the world’s most commonly taken drugs could be even more beneficial than advertised. A new study this month shows that metformin may potentially slow aging in the body and brain of monkeys. While more research in humans will be needed to confirm these findings, the drug is both cheap and already widely available.
Metformin is an invaluable drug that’s long been safely used to treat type 2 diabetes and is on the World Health Organization’s list of essential medicines. In these individuals, it helps lower their blood sugar levels. Metformin has also been used an off-label medication for weight loss (with modest effects) and to manage symptoms of the hormonal condition polycystic ovary syndrome, or PCOS. Over the years, some research has suggested that the drug’s bodily effects, particularly in reducing inflammation, might make it even more useful. The most tantalizing of these studies have suggested that metformin can improve brain functioning and slow down cognitive decline in older patients. While metformin may not directly extend our lifespan, it could possibly lengthen our “healthspan“—the amount of time we spend in relatively good health.
Much of the evidence for metformin’s anti-aging benefits has come from indirect observational data or from studies of animals that aren’t too closely related to humans, such as rodents. But in their new study published last week in the journal Cell, a large group of researchers in China have taken an important step forward in addressing this data gap.
The scientists conducted a 40-month-long study with adult male cynomolgus monkeys (Macaca fasciucularis), roughly equal to 13 years of human life. They regularly gave metformin to 12 older monkeys during that study period, and compared the health of these monkeys to two different control groups not given the drug: one group of 16 older monkeys and another group of 18 young to middle-aged monkeys.
Based on an extensive array of tests, including brain scans, the researchers created a model to estimate the monkeys’ expected and actual biological age across different organs. And the monkeys on metformin tended to show signs of slower aging compared to elderly monkeys not taking the drug, particularly when it came to their livers and brains. According to the researchers’ calculations, the metformin had made these monkeys’ brains six years younger on average, which could potentially translate to 18 years in humans.
“Our research pioneers the systemic reduction of multi-dimensional biological age in primates through metformin, paving the way for advancing pharmaceutical strategies against human aging,” the researchers wrote.
This appears to be the first direct test of metformin’s anti-aging potential in primates. But the study’s findings are still based on a small sample size, and cynomolgus monkeys may have important biological differences that could affect the activity of metformin. These caveats mean that we can’t be certain about metformin’s fountain-of-youth effect in humans, at least not yet. But the results certainly do provide more incentive to keep digging.
The researchers have already begun to work, in partnership with the company Merck, on a Phase II trial that will test metformin as an anti-aging drug in 120 people. And this isn’t the only potential victory for metformin this month. On Tuesday, researchers sponsored by the NIH published a study finding that people taking metformin for their diabetes were less likely to die from their covid-19 infection or to develop long covid than people taking other diabetes drugs—the latest piece of evidence to suggest that metformin could be a valuable long covid treatment.
