Deep brain region could be crucial for preserving physical strength during aging

A new study suggests that a little-known region deep in the brain could be crucial for preserving physical strength as we age. The findings could help detect and prevent frailty before it begins.

Researchers at the University of California, Riverside, used functional MRI scans to measure brain activity in older adults as they performed a simple but critical task: squeezing a device with as much force as possible. That squeeze, known in clinical circles as a maximum grip strength test, is increasingly seen as a window into physical resilience and vulnerability.

Grip strength is more than just muscle. It's a marker of how well your body and your brain are functioning as you get older."

Xiaoping Hu, a UCR bioengineering professor and senior study author

What the researchers found surprised them. Among the dozens of brain areas monitored, one emerged as the strongest predictor of grip strength: the caudate nucleus. Tucked deep in the brain, the caudate is known for helping manage movement and decision-making. But its role in muscular strength, and its potential to signal frailty, has until now gone largely unnoticed.

Amin Ghaffari, a doctoral researcher in Hu's lab and first author of the study published in Frontiers in Neuroscience, explained that the team used advanced models to compare each participant's grip force to a full map of their brain's internal communication system, otherwise known as a "functional connectome."

"It's like mapping out all the phone lines in your brain and seeing which ones are linked to how hard you can squeeze," Ghaffari said. "And one of the clearest signals came from this network involving the caudate."

The researchers analyzed scans from 60 older adults who live in the Riverside area. The study group comprised half men and half women, and all completed three sessions of functional MRI while undergoing strength testing. To ensure they were isolating brain effects from other factors like body size, the data was normalized to account for differences in sex and muscle mass.

The result was a statistically significant correlation between brain network patterns and grip performance. Stronger blood flow and connectivity in the caudate nucleus matched higher grip strength, independent of gender.

Other regions, such as the tail of the hippocampus, which is involved in memory, and the anterior cingulate cortex, linked to emotion and attention, also showed some connection to grip performance. But the caudate's role was most prominent, suggesting it may act as a central hub for physical capacity in aging adults.

The study is among the first to examine grip strength in the context of active brain imaging during a motor task. Unlike previous work that looked at brain structure or rest-state activity, this research captured neural function in real time while participants exerted physical effort.

"This could eventually help clinicians spot frailty earlier, by identifying patterns in brain activity before people begin to lose strength," Hu said.

Frailty, defined as reduced ability to recover from illness or injury, affects millions of older adults. It's not limited to muscle loss but involves a complex interplay of physical, cognitive, and emotional decline. Grip strength has emerged as one of its simplest and most reliable indicators.

By connecting that physical measure to specific brain networks, the UCR team hopes to create a new kind of diagnostic tool and, one day, a target for therapies or training programs aimed at slowing decline.

"Just as you might strengthen muscles with exercise," Ghaffari said, "we could envision ways to strengthen these neural connections through targeted interventions."
While more research is needed to confirm the findings in larger and more diverse populations, the results provide a promising clue in the puzzle of how aging affects the brain, and how the brain, in turn, influences the aging body.

"We're trying to understand aging not as a single event, but as a process," Hu said. "And of course we hope, long term, that more specific and accurate predictions about how people will age can reduce the worst effects of aging."