How Early Can Brain Aging Be Detected? What 1,400+ Brain Scans Reveal

When you think about brain aging, you might picture someone in their 70s or 80s experiencing changes in memory or thinking. But researchers are increasingly finding that the brain's aging process begins much earlier, and that people of the same age can have surprisingly different brain-health profiles.

One way researchers are studying these differences is by using brain imaging to estimate how "old" a person's brain appears based on patterns of brain structure or function. Previous studies have linked an older-than-expected brain age with poorer cognition and mental health, although much of that research has focused on older adults or clinical populations.

Now, researchers of a new study1 specifically looked at brain aging differences in young and middle-aged adults (and whether some of these changes are also linked to gut health). Here's what you need to know.

About the study

The researchers wanted to determine whether differences in brain aging could be detected in young and middle-aged adults, and whether those differences were associated with cognitive and emotional health. They also wanted to explore whether brain aging was connected with biological signals originating in the gut. They also wanted to explore whether brain aging was connected with changes in the gut microbiome.

For brain aginging

For gut health

"Older" brain connectivity was linked to poorer cognitive performance

Results showed that a higher brain aging index was consistently associated with poorer cognitive performance, particularly in areas involving working memory and executive function. Working memory helps us temporarily hold and manipulate information, while executive function encompasses skills such as planning, attention, mental flexibility, and impulse control.

These findings build on previous research linking advanced brain age with cognitive performance, but extend those observations into younger and middle-aged adults.

The researchers also found that a higher BAI was associated with greater depressive symptoms.

Importantly, these findings don't mean that having an older brain age causes cognitive problems or depression. The study was observational, so it can't establish which comes first or whether another factor contributes to both.

Brain aging was also associated with gut microbes & metabolites

When researchers integrated the brain imaging data with stool microbiome and metabolomic data, they found that certain microbial taxa and metabolites were associated with differences in BAI.

Among the metabolites identified were ceramides, 24-hydroxycholesterol, and dicarboxylic acids, as well as an inverse association with estetrol.

The researchers then looked at the biological pathways connected to the features that were most strongly associated with brain aging. These pathways included processes involved in neuroimmune signaling, vascular function, synaptic activity, and mitochondrial function.

All of these systems are relevant to brain health. Mitochondria, for example, are responsible for producing much of the energy brain cells need, while healthy blood vessels are essential for delivering oxygen and nutrients to the brain. Synapses allow neurons to communicate, and neuroimmune signaling helps regulate interactions between the nervous and immune systems.

What this means for your brain health

Brain aging isn't necessarily something starts later in life. Differences in brain connectivity associated with aging were detectable in young and middle-aged adults and were linked with measures of cognition and mood.

And while you can't control everything related to cognitive decline, your habits do strongly influence brain aging processes. Whether you're in your 20s or 70s, here are some habits that support brain health.

The takeaway

Your actual age doesn't always equal the age of your brain. This study suggests that differences in brain connectivity are detectable earlier in adulthood and are associated with cognition, mood, and gut-related changes. The good news is that's it's never too early (or too late) to build habits that support your brain health now and for years to come.