Brain Changes with Age: Surprising Findings

It’s often assumed that aging naturally leads to brain deterioration, but recent research challenges this view, especially concerning the brain’s somatosensory cortex—the area responsible for processing sensory information.

New analyses of both mouse and human brains indicate that certain regions within this cortex not only resist the expected thinning that occurs in other areas but may actually become stronger with age. This finding hints at the brain’s remarkable ability to adapt, suggesting that continued use could enhance its strength over time.

“Previously, we hadn’t considered that the primary somatosensory cortex is made up of several extremely thin layers, each serving distinct functions. We’ve discovered that these layers age in varied ways,” explains Esther Kühn, a neuroscientist at the German Center for Neurodegenerative Diseases and the Hertie Institute for Clinical Brain Research.

Despite the overall thinning of the cerebral cortex, some layers remain stable or even thicken as people age, likely because they are more frequently engaged and thus maintain their functionality. This points to neuroplasticity—essentially, the brain’s adaptability—even in older individuals.

Neuroplasticity is often thought to peak in youth and wane with age, yet this assumption may not be entirely accurate, as evidenced by the lack of strong support for the notion that brain plasticity drastically decreases over time.

Under the guidance of neuroscientists Peng Liu and Juliane Doehler from Otto von Guericke University in Germany, a study examined age-related changes in the human cerebral cortex, a region known to typically thin as one ages.

“Conventional wisdom suggests that diminished brain volume equates to decreased function,” Kühn notes. “Yet, we know surprisingly little about how the cortex actually ages. Given that many daily functions depend on it, we utilized high-resolution brain scans to delve into this matter.”

The researchers conducted detailed MRI scans on 61 adults aged 21 to 80, zeroing in on the primary somatosensory cortex, which relays touch information. They found this area resembles a stack of crepes—made up of multiple delicate layers, each with specific roles. These layers appeared differently based on the individual’s age.

Some layers thinned in older individuals, which was expected; however, the middle and upper layers were found to be thicker as people aged compared to younger counterparts.

“The middle layer acts as a gateway for touch stimuli, while the upper layers process this information further,” says Kühn. For example, in terms of sensory input from the hands, the upper layers facilitate interactions between fingers, which is essential for grasping objects effectively.

Conversely, the lower layers were thinner in older participants. These layers are responsible for modulating tactile signals, adjusting their amplification based on context. For instance, we often don’t notice our clothing unless we consciously think about it—much like how the brain tends to overlook our noses in our field of vision.

The researchers propose that the varying thickness of these layers could be tied to the old saying of “use it or lose it.”

“The middle and upper layers interact continuously with external stimuli and remain active because we’re always engaged with our surroundings,” notes Kühn. “In contrast, the lower layers receive less stimulation, especially in later years. This suggests that our findings indicate the brain preserves what it heavily relies on—an illustration of neuroplasticity.”

Interestingly, while the lower layers reduce in size, they may mitigate any cellular loss. The researchers observed an increase in myelin content, correlated with a rise in a specific neuron type that strengthens modulation signals.

This adaptability is promising, and the team hopes future work might foster these mechanisms even more.

“Our findings align with the idea that we can positively impact our brains through appropriate stimulation,” Kühn asserts. “It’s an encouraging thought that we might have some influence over our aging process.”

The research has been published in Nature Neuroscience.