A small clinical trial published on Tuesday revealed that a drug from the GLP-1 receptor agonist class, known for its weight loss properties, slowed the reduction of brain volume in individuals with mild Alzheimer's disease. The findings, presented at the Alzheimer's Association International Conference, mark the initial indication of how GLP-1 drugs might influence difficult-to-treat brain conditions. The study involved 204 patients in the UK, with half receiving Novo Nordisk's earlier-generation GLP-1 drug liraglutide, and the other half a placebo. Although the trial failed to achieve its primary objective, which was a change in cerebral glucose metabolic rate, it did meet secondary objectives. It demonstrated that liraglutide seemed to decrease brain shrinkage in areas responsible for memory, learning, language, and decision-making by nearly 50 percent compared to the placebo. The trial was not funded by Novo Nordisk. However, the Danish pharmaceutical company is currently testing its new-generation, more potent GLP-1 drug semaglutide—marketed as diabetes drug Ozempic and obesity drug Wegovy—in thousands of early Alzheimer's patients. The two trials commenced in 2021, with results anticipated in 2025.

Rebecca Edelmeyer, the senior director of scientific engagement at the Alzheimer's Association, described the published results as "really intriguing" in an interview with Reuters. "This is our first time really seeing this type of intervention readout in a clinical trial," she noted. Researchers previously told Reuters that diabetes treatments, ranging from Ozempic to insulin and metformin, seem to tackle various aspects of the metabolic system linked to Alzheimer's, including amyloid proteins and inflammation. The hope is that enhancing glucose utilization and reducing inflammation throughout the body, including the brain, could decelerate the progression of Alzheimer's. However, the trial published on Tuesday was not intended to assess cognitive benefits, prompting some scientists to advocate for caution.

Stephen Evans, an emeritus professor at the London School of Hygiene and Tropical Medicine, stated that the repurposing of drugs is a significant area of research but carries much uncertainty. He noted that the observed brain shrinkage in areas related to memory and learning in the small trial "may not translate to significant cognitive benefits" and that the results did not prove that liraglutide could prevent dementia. Nonetheless, he suggested that pursuing a larger trial would be beneficial.