Our Brains Were Wired To Move.

For millions of years, our ancestors moved – walking, running, climbing – as an integral part of daily life. Today, most of the modern world doesn’t move nearly as much as we were designed to, and new research suggests that it’s one of the major factors contributing to the rise in dementia and Alzheimer’s.

A new study from UT Southwestern suggests that the lower the fitness level, the faster the deterioration of vital nerve fibers in the brain. This deterioration results in cognitive decline, including memory issues characteristic of dementia patients. It supports the hypothesis that improving people’s fitness may improve their brain health and slow down the aging process.

The study, published in the Journal of Alzheimer’s Disease, focused on a type of brain tissue called white matter, which is comprised of millions of bundles of nerve fibers used by neurons to communicate across the brain. The researchers determined that lower fitness levels were associated with weaker white matter, which in turn correlated with lower brain function.

Unlike previous studies that relied on study participants to assess their own fitness, the new study objectively measured cardiorespiratory fitness with a scientific formula called maximal oxygen uptake. Scientists also used brain imaging to measure the functionality of each patient’s white matter.

Patients were then given memory and other cognitive tests to measure brain function, allowing scientists to establish strong correlations between exercise, brain health, and cognition.

The Science of Preventing & Treating Dementia With Exercise

Exercise increases the presence of a nerve growth factor called BDNF (brain-derived neurotropic factor). Think of BDNF as fertilizer for the brain. It helps strengthen neural connections as well as form new ones and maintain old ones.

Along with the increase in BDNF, exercise results in an increase in blood flow to the brain. Better circulation brings more nutrition to brain structures and helps metabolize and remove waste products from the brain. It also stimulates angiogenesis, or the creation of new blood vessels.

Finally, exercise benefits the brain through several other additional mechanisms: it helps normalize blood sugar levels, increases oxygen intake, and aids in sleep. Sleep is great for the brain; the brain metabolizes much of the plaque associated with Alzheimer’s and other metabolic waste while sleeping at night.

How Much Exercise Is Enough?

It’s tough to answer exactly how much exercise each of us needs because there are so many variables: age, body composition, and exercise intensity and duration. For older adults, studies with walking interventions saw an increase in cognitive skills, hippocampal size (an area of the brain important for memory, and hit hard by Alzheimer’s), and reduced the presence of amyloid-beta (associated with Alzheimer’s and dementia). In general, younger adults require more intense exercise to see the same benefits.

For the acute effects of exercise on cognition (e.g., if I go for a run will I be better on a cognitive test 1hr later?), there is a dose-effect relationship. Meaning that the more intense, the greater the cognitive benefit after exercise.

The study adds to a growing body of evidence pointing to a simple yet crucial requirement for staying healthy: exercise regularly.

The Bottom Line

Science is helping push the fact that our bodies need regular excercise, a healthy diet, adequate sleep and regular daily schedules in order to maintain them. It’s something we’ve known forever but something that’s easy to forget when life gets busy.

Sources:
Ding K. Cardiorespiratory Fitness and White Matter Neuronal Fiber Integrity in Mild Cognitive Impairment. Journal of Alzheimer’s Disease. 2018;61(2):729-739.
Gomez-Pinilla F, Hillman C. The Influence of Exercise on Cognitive Abilities. Comprehensive Physiology. 2013;3(1):403-428.f