Semaglutide Extended Elderly Mice’s Lives in a Study of Aging

Semaglutide, the active ingredient in drugs such as Ozempic and Wegovy, extended the median life span of elderly female mice by 12 percent in a new study, while also improving several measures of physical and cognitive performance. Researchers gave daily semaglutide injections to female mice that were 20 months old—roughly equivalent to 60-year-old women—and continued the treatment for the rest of the animals’ lives. A comparison group received saline injections. The mice treated with semaglutide lived a median of 834 days, compared with 742 days for the saline-treated animals. The study, published in Nature on September 2, was based on the idea that GLP-1 medicines might imitate some effects of calorie restriction. Semaglutide reduces food intake by promoting feelings of fullness and helps regulate blood sugar. The treated mice reduced their own food consumption by 24 percent. After three months, the semaglutide-treated animals were described as more active and curious than the control mice. They performed better on several tests, including balancing on rotating rods, running on a treadmill and navigating a maze. Molecular testing also found lower levels of cellular features associated with aging, including DNA damage and inflammation. The researchers compared the drug-treated mice with animals whose diets had been deliberately reduced by the same 24 percent. Both groups showed similar life spans and performed similarly in some endurance and motor-coordination tests. However, the semaglutide group did better on tests involving memory and exploration and had improved glucose tolerance. The findings suggest the drug’s effects may involve more than reduced calorie intake, though the mechanism remains unknown. The study included only female mice because the researchers considered male mice more aggressive, which could have complicated the results. Scientists not involved in the research said further testing is needed, particularly because findings in one sex may not apply to the other. Researchers also raised a concern about muscle loss, a potential consequence of GLP-1-associated weight loss that could be especially significant for older adults already experiencing age-related muscle decline. The study does not establish that semaglutide extends human life span.