In nearly 1,500 adults, an older-looking brain lined up with specific gut bacteria and weaker working memory

What the research found

Study (cross-sectional, three groups). Kanhao Zhao, Arpana Church, and colleagues at UCLA report in eBioMedicine (2026; 132:106468; DOI 10.1016/j.ebiom.2026.106468). They estimated a Brain Aging Index from resting scans of how brain regions communicate, in nearly 1,500 generally healthy young and mid-life adults. A higher index, meaning the scan looked older than the person's age, lined up with weaker working memory and executive function and with more depression symptoms. In the group that also gave stool samples, a higher index lined up with particular gut bacteria and metabolites, including some fat molecules, a cholesterol-related compound, and lower estetrol. Church, at the Goodman-Luskin Microbiome Center, says the signals may be visible decades before obvious cognitive disease. This does not show that changing the gut slows brain aging, and it is not a dementia diagnosis. Not medical advice.

Evidence level: Human study. A study in people, but an association isn't proof of cause.

Read the original at UCLA / eBioMedicine