A new way to measure brain age
A study from UCLA Health has found a link between the bacteria living in the gut and how fast a person's brain ages. The work was published in the journal eBioMedicine.
Researchers built a Brain Aging Index from brain scans of generally healthy adults. The index compares the brain's functional connections with what would be expected at a given age. A score above zero means the brain looks older than the person's years.
What the gut showed
In one group of participants, the team also studied stool samples. A higher Brain Aging Index was linked to specific gut bacteria and to chemical byproducts they produce.
Those byproducts included certain fat molecules, a cholesterol-related compound and lower levels of a hormone called estetrol. The biological pathways involved pointed to the immune system, blood vessel function, communication between brain cells and how cells make energy.
People with older-looking brains also performed worse on tests of memory, attention and mood. The differences were measurable even though the participants had no diagnosed cognitive problems.
Early signals, not proof
The study is cross-sectional, which means it took a single snapshot of each person. It can show that two things move together, but it cannot prove that gut bacteria cause brain aging.
Senior author Dr. Arpana Church, co-director of the Goodman-Luskin Microbiome Center at UCLA Health, said the biological signals may be detectable decades before symptoms appear. She said the findings could one day help identify who is at risk and where to intervene.
Researchers say the next step is to follow people over time and to test whether changing diet or the microbiome affects the index. Until then, the gut is a promising lead rather than a proven lever.