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How exercise reorganizes the brain to reduce anxiety

Kathleen Blanchard's picture
Princeton researchers uncover why exercise can make us less anxious

We all know stress can lead to a variety of health problems in addition to contributing to a shorter lifespan. Now research from Princeton University shows exercise can reorganize the brain to help us cope with everyday stressors by reducing anxiety that can have a long-term negative impact on health.

Stress releases hormones that can lead to cardiovascular disease lack of sleep, obesity and more. Finding non-drug approaches for dealing with stress is important for public health.

For their study, published in the Journal of Neuroscience, Elizabeth Gould, Princeton's Dorman T. Warren Professor of Psychology and colleagues subjected mice to stress by subjecting them to cold water.

Exercise turns off excitable brain neurons

Brain mapping showed exercise turned off neurons in an area of the brain that controls anxiety, known as the hippocampus.

There’s been some discrepancy about what happens in the brain that makes us less anxious when we engage in regular physical activity.

According to background information from the researchers exercise should cause more anxiety because neurons in the hippocampus of the brain when are less mature than other brain cells and therefore more excitable.

Research has suggested exercise reduces anxiety while promoting the growth of new neurons in the ventral hippocampus.

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The Princeton researchers found exercise strengths areas of the brain that prevent the neurons from firing.

Understanding how exercise regulates anxiety could mean new treatments

Gould says the impact of exercise on the ventral hippocampus has not been studied in depth. The new research could help with new treatments for helping humans with anxiety disorders.

"Understanding how the brain regulates anxious behavior gives us potential clues about helping people with anxiety disorders. It also tells us something about how the brain modifies itself to respond optimally to its own environment," said Gould, who also is a professor in the Princeton Neuroscience Institute.

She also explains the brain is resilient in terms of adapting to its own processes and surroundings. A less physically fit person might be more anxious as a survival mechanism. She says anxiety of often manifested by ‘avoidance behaviors’ and avoidance of potentially dangerous situations that would put them at risk from lower ability to respond with a ‘fight or flight’ reaction.

In group of experiments sedentary and active mice were tested. Only one of the two groups was given unlimited access to a running wheel. Gould explains mice that are ‘natural runners’ will go about 2.5 miles a night when they can freely access a running wheel.

After six-weeks the researchers briefly exposed the mice to cold water. Following the exposure the scientists viewed how differently the brain reacted to stress between the two groups that occurred almost immediately.

The study results showed short-lived genes known as ‘immediate early genes’ instantly turned on in sedentary mice, but the brains of active mice showed control.

Active mice had an increase in the release of the brain chemical GABA - gamma-aminobutyric acid – that acts as an inhibitory control for neural excitement. They also stored more of the chemical. When the researchers blocked GABA, the effect of exercise on controlling anxiety was cancelled.

The finding shows exercise reorganizes the brain to help manage stress and builds on past studies about the benefits of exercise that can improve our mental and physical well-being.