UCLA study linked brain aging to gut microbiota — ScienceDaily

In the United States, UCLA Health researchers found a link between a higher brain aging index, the composition of the gut microbiota, and certain metabolites. Participants whose brains appeared older than their chronological age based on scans generally performed worse on working memory and executive function tasks and more often reported symptoms of depression, ScienceDaily reports.

How brain age was assessed

In the study, published in the journal eBioMedicine, scientists analyzed brain scans from nearly 1,500 adults across three separate groups. They used a method that assesses interactions between different brain regions at rest and created a computer model to determine predicted brain age.

The authors called the difference between the age estimated by the model and the participants' actual age the Brain Aging Index. A higher score meant that, based on patterns of functional connections, the brain appeared older than would be expected given a person's chronological age.

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Microbiota and metabolites

In one group of participants, the scientists also examined stool samples. A higher brain aging index was associated with certain gut bacteria and several metabolites, including specific fatty molecules, a cholesterol-related compound, and lower levels of the hormone estetrol.

Pathways associated with these biological signals involve the immune system, blood vessel functions, communication between brain cells, and cellular energy production. The study's senior author, UCLA Health Goodman-Luskin Microbiome Center co-director Arpana Church, said that biological signs of brain aging may be detected decades before obvious problems with memory or thinking emerge.

The study is cross-sectional and describes the identified associations between indicators rather than proving that gut bacteria cause faster brain aging.