Metformin preserved brain volume and connectivity in older adults
In a 40-week randomized trial of 40 older adults with insulin resistance, metformin preserved regional brain glucose uptake, volume and coordination between brain regions.
72 adults, placebo-controlled
Limit: The brain-preservation finding comes from only 40 older adults
Edited by Boris Djordjevic · AgingResearch.News
Researchers randomly assigned 40 older adults with insulin resistance—a reduced response to the hormone insulin—to metformin or placebo for 40 weeks. They repeated brain scans and tests of thinking skills after this period.
Metformin improved insulin sensitivity while preserving blood-sugar uptake, volume and functional connectivity—the coordination of activity between brain regions—in specific regions involved in decision-making and learning. It was also associated with a better combined measure of processing speed and working memory, the ability to hold and use information briefly. In a broader assessment of 72 adults with or without markers of insulin resistance, those markers were associated with smaller brain volumes and reduced coordination between brain regions.
Why it matters
Insulin resistance is a modifiable risk factor for dementia. The trial supports the idea that improving the body's response to insulin may help prevent brain deficits in older people with insulin resistance.
Caveats
The 40-person trial assessed brain measures and thinking skills rather than dementia prevention. Its findings concern older adults with insulin resistance; the abstract did not give the metformin dose or report harms.
Metformin is part of Bryan Johnson's Blueprint and David Sinclair's daily regimen in Lifespan
The paper
Mayo Clinic
The Journal of Clinical Investigation, Oct 27, 2026, Open access
