Your brain is a glucose-hungry organ containing nearly 86 billion cells called neurons. The brain compartmentalizes these neurons into different regions and sub-regions that perform a specific function. Neurons communicate with each other through electrical and chemical signals delivered over junctions called synapses.
These specialized areas are responsible for our growth and development from birth to old age. And according to a review published in Psychophysiology, the way the brain links and communicates undergoes a significant “rewiring” starting in midlife. The changes in connections have an impact on our cognitive abilities and may be the brain’s solution to function as efficiently as possible with aging “hardware.”
A Systematic Review: 1986-2021
Australian researchers from Monash University examined scientific literature on the brain to better understand what contributes to cognitive decline with old age. They looked at 144 studies including tens of thousands of brain scans.
The brain scans revealed which parts of the brain “light up” or activate in response to certain stimuli. The data illustrated the brain’s interconnectivity, and the researchers could determine how these connections changed with age.
They found that in our younger years, the brain appears to have many separate regions with robust inner connectivity, which make specialized processes—like learning a sport or a language—easier. Around the mid-40s, the brain shows fewer connections between these separate regions and rather broader connectivity as a whole.
This would explain what researchers noted in how we think about and view the world as we age.
“Older adults tend to show less flexible thinking, such as forming new concepts and abstract thinking, response inhibition, as well as verbal and numeric reasoning,” researchers noted. “These findings are also consistent with a decline in executive functions but maintenance of primary information processing in ‘normal’ aging, which implies an underlying compensation mechanism in aging to support higher-level cognitive functioning.”
Working With Dwindling Resources
So, why does the brain decide to reroute its connections in midlife? The simple answer is a simple sugar: glucose. Glucose is the brain’s primary energy source, using 20% of the body’s overall glucose supply while only accounting for 2% of the total body weight.
As we age, our brains become less efficient when metabolizing glucose. The less glucose our brains can “eat,” the less efficiently it can supply enough energy to maintain highly-specialized, internally-connected brain regions. Thus, the connections become broader, more generalized, and less specifically functional.
Imagine a piece of woven cloth. The tighter and more plentiful the strands, the sturdier and less prone to wear and tear the material becomes—but creating this weave is labor-intensive. Alternatively, the same fabric can be woven more quickly and with less effort by using longer, looser strands. But this type of fabric is also flimsier and more prone to damage.
How To Keep Your Mind Sharp
The brain certainly changes in many ways as we age, but they aren’t all negative. For example, researchers found that tasks relying on “predominantly automatic or well-practiced processes are less impacted by age or may even increase slightly across the lifespan.” This includes areas of brain function responsible for vocabulary and general knowledge.
Speech and language processing tend to be relatively stable with age, the study said, although a generalized reduction in processing speed may make response times slower in older adults. And generally speaking, there are several things you can do to keep your mind sharp well past your 40th birthday.
A proper diet (nutrients are vital for proper brain function), regular exercise, and healthy lifestyle choices can prevent the severity of cognitive decline with age. The scientists who worked on this review said further research is needed to better understand the inner workings of the brain’s rewiring phase and, in turn, how to avoid its more adverse side effects.
So, before dogging yourself for your third “senior moment” or “menopausal brain fog” incident of the day, remember that your brain is rerouting its entire roadmap. Give yourself grace while you experience and respond to these changes.