A new study from UCLA Health suggests that the pace of brain aging is connected to the bacteria living in the gut and the chemical compounds they produce. The findings, published in the journal eBioMedicine, indicate that biological changes linked to cognitive decline may begin long before noticeable problems with memory or thinking appear.
Scientists have long used brain scans to estimate a person’s “brain age,” a metric that can differ from their actual chronological age. Previous research established that when a brain appears older than expected, it often correlates with poorer memory, weaker thinking skills, and mood changes. However, most earlier studies focused on older adults or individuals with existing neurological conditions, leaving a gap in understanding how these patterns affect younger, generally healthy people.
UCLA Study Methodology and Findings
To address this gap, researchers examined brain scans from nearly 1,500 adults divided into three separate groups. The team used a scanning approach that measures how different areas of the brain communicate while a person is at rest. They then built a computer model to estimate each participant’s age based on these communication patterns.
The difference between the estimated brain age and the actual chronological age became what the researchers called the Brain Aging Index (BAI). Across all three groups, participants with a higher BAI generally performed worse on tests of working memory and executive function. These abilities are essential for holding information in mind, staying focused, and organizing tasks.
People with a higher Brain Aging Index also reported more symptoms of depression. The patterns consistently involved brain regions associated with memory and self-referential thought, which are the mental processes people use when thinking about themselves and their own experiences.
Gut Microbiome and Metabolic Byproducts
For one of the study groups, the researchers analyzed stool samples to determine if differences in brain aging were connected to changes in the gut. They found that a higher Brain Aging Index was associated with specific gut bacteria and several metabolic byproducts. These included certain fat molecules, a cholesterol-related compound, and lower levels of a hormone called estetrol.
The pathways connected with these biological signals involved the immune system, blood vessel function, communication between brain cells, and the processes cells use to produce energy.
“Brain aging doesn’t suddenly begin when we get older, but the biological signals may be detectable decades earlier,” said Dr. Arpana Church, the study’s senior author and co-director of the Goodman-Luskin Microbiome Center at UCLA Health. “By linking these early brain changes with the gut microbiome and its metabolites, we are beginning to identify pathways that could ultimately help us understand who may be at risk and, importantly, where we might intervene to support healthier brain aging.”
Church noted that these findings may eventually help researchers identify people at greater risk of cognitive or mood-related decline earlier in life. The results also raise the possibility that the gut could become a target for future strategies designed to support brain health and prevention earlier in life.
Source: ScienceDaily
