Neural networks made up of two sections make up the brain. The wiring that links the cellular “gray matter” of neurons and dendrites is known as “white matter.” White matter shrivels and diminishes with age in sedentary people, a clinical connection of which can be memory loss, difficulty finding words, and a general decline in cognition known as dementia.
Physically active individuals, by contrast, keep their white matter robust. Increased physical activity can even expand the amount you have to work with.
Our dynamic brains constantly rearrange themselves in response to sensory inputs and motor feedback. Our brain networks self-adjust to stimulation, experience, and context. They also self-assemble.
This is a remarkable example of plasticity (Greek, plastikos means “to mold”) because the fact that adult brains can change at all is a fairly recent discovery. The belief that adult brains are incapable of developing new nerve cells or altering their patterns of ingrained behavior and habits persisted into the 1990s. According to conventional wisdom, your brain has all the cells it will ever have when you are born, so as you age, your brain will inevitably start to function less well.
Today, it is generally recognized that neurogenesis, or the production of new brain cells, occurs in a number of areas of the brain, particularly the hippocampus, which is in charge of creating new short-term memories that are later transported to the cortex for long-term storage. Studies on neurogenesis have shown an unexpected conclusion: exercise increases the effect. Aerobic exercise increases brain volume in both rats and people.
A multi-institutional study including 250 older people who were sedentary but otherwise healthy was coordinated by Colorado State University. All of them underwent baseline scans before being divided into three groups.
The first group (the control group) performed balance and flexibility drills three times a week. The third comparison group engaged in line dancing and group choreography three times per week, while the second test group walked briskly for 40 minutes three times each week. After 6 months, each group underwent follow-up scans.
Objectively, both the walkers and dancers were more aerobically fit. Even while both cohorts now had more connections to their white alma maters, the rise was more noticeable in the walkers. In contrast to dancers, walkers improved their performance on memory tests. Conversely, those in the control group who had not engaged in any aerobic activity displayed shrinking white matter and declining cognitive scores.
According to the results (and those of related studies), white matter is still pliable and active as people age, and taking a few brisk 40-minute walks each week may be enough to stave off memory loss.
The study also demonstrates how science is counterintuitive. In other words, it can be risky to rely on “it stands to reason” reasoning rather than genuine experimentation that yields concrete results. It might seem obvious that if any aerobic exercise is beneficial, then more, like dancing or even running, must be even more beneficial.
But this proved not to be true. Not only did walking enhance the amount of white matter in the brain, but it also caused the prefrontal cortex to grow significantly. The prefrontal cortex is one of the first brain regions to deteriorate in different types of dementia. It is involved in judgment, reasoning, planning, and temperament.
The relative health of immune cells within the central nervous system (microglia) that cope with infections and inflammation is high in people who lead more active lifestyles, which also lowers dementia risk.
A surprising corollary of this research can act as a warning: In instance, hippocampal shrinkage and ventricular enlargement may be early markers of brain degeneration in those with decreasing gait. Sluggish gait is linked to cognitive deterioration and Alzheimer’s disease, and slow gait is associated with a high energy expenditure for mobility.
We still aren’t completely sure why exercise leads to heftier brain tissue and better thinking, but simply walking can keep you sharp as you age.