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How Physical Activity Sharpens the Mind

What the brain does is greatly connected to what the body does.

Key points

  • The brain evolved to control movement, but movement also shapes our thinking.
  • Physical activity is often used by artists and scientists to boost their creative problem-solving.
  • Exercise reduces anxiety and depression in the general population.

The brain evolved to control movement, but movement also shapes our thinking. This truth cuts across neuroscience, clinical psychology, exercise physiology, and the psychology of aging.

Brain Cells and Problem-Solving

The ancient Romans linked a healthy brain to having an active body. Highly educated individuals live longer than their less-educated counterparts, suggesting that an active brain also contributes to a healthy body.1 One explanation for this phenomenon is that people with more active minds have better circulation of blood in their brains, This makes them less vulnerable to brain aging and senile dementia.

Canadian neuroscientists found that voluntary exercise greatly increases the proliferation of stem cells in the dentate gyrus of the hippocampus, so an avid walker benefits from having more cells. Such benefits accrue from as little as a half hour of walking each day.

The hippocampus plays a key role in forming new memories and is also implicated in spatial problem-solving.

No wonder that physical activity is often used by artists and scientists to boost their creative problem-solving, whether they are poet William Wordsworth or evolutionary biologist Charles Darwin.

In addition to the direct consequences of physical activity for brain anatomy and physiology, there is an indirect effect via elevation of mood.

Activity and Mood

Exercise reduces anxiety and depression in the general population and can even be an effective treatment for anxiety disorders and clinical depression. These effects are not well understood, but they likely reflect changes in neurotransmitter systems, such as serotonin, norepinephrine, and endorphins.

However, mood is elevated by exercise, which generally stimulates cognitive activity and creativity. Extremely creative individuals sometimes experience manic phases during which they are unusually productive. So, an elevated mood is conducive to increased mental activity and creative productivity.

On the other hand, people who are anxious, sad, or depressed often have trouble initiating, or completing, creative endeavors.

There are many different ways of looking at the connection between physical movement and mental activity. One of the most prosaic is that exercise stimulates increased uptake of oxygen and boosts the circulation of the blood.

Circulation in the Brain

Physical activity boosts respiration. This means that our breathing rate increases and more oxygen is transported through the bloodstream. A fraction of this oxygen ends up in the brain where it expends glucose, which is the brain's primary fuel.

In general terms, this means that physical activity of any kind tends to stimulate alertness and thought processes. So, a person who is deprived of sleep can stay alert by doing exercises.

A healthy brain is an extension of a healthy body, and a healthy mind is an extension of a healthy brain.

These connections are of great practical importance. So, a person who suffers from anxiety and depression is also at greater risk of developing heart disease because the emotions a person experiences get projected onto their body. Another practical consequence of physical activity is that those who remain physically active in old age benefit from sharper thinking and even from increased longevity.

Longevity

It seems that an active brain contributes to general health and longevity. This could be partly why people who earn a college degree are more long-lived. (We must be careful about drawing such conclusions because group differences in life expectancy are complex and are affected by influences as different as chemical pollution and psychological stress.)

People who live in communities where there are many centenarians tend to stay active in terms of physical exercise, social engagement, mental stimulation, creativity, and work. These propensities keep their brains active and, in so doing, could delay the onset of senile dementia.

Among the many possible reasons for cognitive decline in old age, one view is that the smallest blood vessels, the capillaries, become blocked, starving neurons of the energy they need to work. Those who are mentally highly active could have a certain amount of redundancy built into the brain such that blood flows to active cells in the brain through alternative pathways. Exercise retunes the brain in ways that promote efficient cognition, slow down age-related dementia, and extend our lives.

References

1. Molla, M. T., Madans, J. H., and Wagener, D. K. ( 2004). Differentials in adult mortality and activity limitation by years of education in the United States at the end of the 1990s. Population and Development Review. 30, 625–646.

2 Olson, A. K., Eadie, B. D., Ernst, C. and Christie, B. R. (2006), Environmental enrichment and voluntary exercise massively increase neurogenesis in the adult hippocampus via dissociable pathways. Hippocampus, 16: 250–260. doi:10.1002/hipo.20157

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