The Neuroscience of Running

Contributed by Prefrontal.org

Just over a year ago I began running as form of regular exercise. I was looking for an outdoor activity that I could do year-round in New Hampshire and found running to be enjoyable in both warm and cold weather. It took a few weeks to (literally) get up to speed, but I have been running an average of twice a week ever since. Over the last year I have begun to collect all of the fitness-related neuroscience articles that occasionally arrive at my inbox. I have been saving a few of them for a short review on the anniversary of my first run. That time has arrived, and so has the post – click to read more.


I. The impact on mood

Endurance training has been shown to have a positive impact on affective state. Runners have known anecdotally about this effect for quite some time, but it is only in the last few decades that the neural underpinnings of this effect have been investigated. One mechanism that seems to be associated with increased positive mood is neurogenesis, or the creation of new neurons.

In a review of 14 studies examining the relationship between exercise and major depression Lawlor and Hopkor (2001) found that the magnitude of the antidepressant effect of exercise is generally equal to that of cognitive therapy. Strawbridge et al. (2002) further found that those who engage in exercise are less likely to develop a depressive disorder to begin with. These antidepressant effects have been shown to persist for over 21 months after exercise has stopped (Singh, Clements, and Singh, 2001). What causes this antidepressant effect?

The common belief used to be that the human brain did not form new neurons after early childhood, but recent evidence has accumulated that certain structures, such as the hippocampus, do create neurons as an adult (Lledo, Alonso and Grubb, 2006). The hippocampus is a structure in the brain known to be involved in memory and learning. In mice voluntary running has been shown to increase neurogenesis in the hippocampus (Naylor et al., 2008; van Praag, Kempermann, and Gage, 1999). The increase in neurogenesis has then been associated with reductions in depressive mood and depressive severity in rats (Bjørnebekk, Mathe, and Stefan Brene, 2005).

Running has also been associated with a reduced response to stress and anxiety. It can not only reduce the effects of a current stressful situation, but acts to guard against future stress (Greenwood and Fleshner, 2008). One source of this effect is a change of activity in the dorsal raphe nucleus (DRN), a center for serotonin in the brain. Hyperactivity in the DRN during stress has been shown to alter the behavior of an animal, often leading to a state of learned helplessness and avoidance (Maier and Watkins, 2005). In rats six weeks of wheel running was shown to significantly reduce DRN activity during uncontrollable stress (Greenwood and Fleshner, 2008). It also reduced the helpless behavior of the rats.

As a society the United States shells out over 25 billion dollars a year on antidepressants. The efficacy of these drugs is generally not as substantial as effects seen after exercise. Exercise also seems to impact a wider array of neural systems, positively affecting everything from single neurons to whole neural systems. Putting all of the above information into perspective, if I could create a pill that would increase positive mood in the same way that running does I would be a billionaire – seriously.

II. The impact on cognition

Exercise has been shown to provide cognitive improvements to both humans and animals. Researchers have observed benefits to long-term memory, learning, attention, executive control, and a host of other cognitive abilities. The brain as a whole seems to thrive on exercise.

One source of cognitive benefit is purely cardiovascular. Exercise increases cerebral blood flow and provides for more efficient glucose utilization (McCloskey et al., 2001). Let’s be clear, the brain lives on glucose. Over 25% of the energy you take in is going to fuel that little three-pound mass in your skull. When you are really working on a tough problem that percentage only goes up as energy usage increases. If you can more efficiently get energy where it needs to go that would represent a major benefit to cognitive processing.

Another source of cognitive benefit has to do with neurons and the environment they inhabit. The same mechanisms of neurogenesis described in section I are known to contribute to cognitive benefits as well (van Praag et al., 1999). Enhancement also is due to an increased level of brain-derived neurotrophic factor (BDNF) present after exercise. BDNF is a protein that helps existing neurons to survive and grow. Elevated corticosterone levels caused by acute stress tend to reduce levels of BDNF in the cortex and hippocampus, while exercise can raise levels significantly above baseline (Adlard and Cotman, 2004; Neeper et al., 1996).

Changes in the regional anatomy of the brain have also been observed after exercise. Grey matter differences in the frontal and temporal lobes were observed in association with individuals who exercise more frequently (Kemppainen et al., 2005). This may be related to the results of Colcombe et al (2004), who found that older adults with better fitness showed significantly higher activity in lateral frontal and superior parietal regions when engaged in an attention task.

Individuals suffering from cognitive deficits show benefits after beginning a new fitness regime. Exercise has been shown to improve the condition of Alzheimer’s patients (Teri et al., 2003) and stroke victims (Shepherd, 2001). While the effects are not gigantic, any improvement in the cognitive outcome of these disorders can greatly help a patient. Further, exercise reduces the risk of cognitive impariment, Alzheimer’s disease, and dementia to begin with (Lautenschlager, 2008; Friedland et al., 2001). This seems to be especially true if you have a genetic predisposition to these disorders.

As an aside, the PsyBlog has a great mini-review of typical cognitive enhancers and finds that between brain training, nutritional supplements, drugs, meditation and exercise that exercise is currently the best-bet for improving your cognitive ability. I tend to agree.

Much like the effect on mood, exercise affects a wide array of neural functions critical to cognition. Not only is there a boost in energy efficiency, but overall there is more energy available to burn. Further, the impact of events that seem to cause the most harm to our brain, such as acute stress, are marginalized and protected against. Together these factors help create a positive neural environment that supports cognitive improvement.

III. High as a kite

I would be remiss not to comment on the “runner’s high” that many people experience after extended exertion. This is often described as a state of euphoria or pleasure that occurs late into a long run. Recent evidence suggests that this state of euphoria is the direct result of engaging the brain’s endogenous opiate system. Boecker et al. (2008) found that strenuous running induced significant opiate binding in orbitofrontal, anterior cingulate, insula, and temporoparietal cortex in addition to multiple limbic and paralimbic subcortical areas. These are brain areas involved in the mapping of body state to emotional state. Their results are bolstered by other studies showing that naloxone, an opiate binding inhibitor, blocks the runner’s high from taking place (Janal et al, 1984).

It makes sense that our brain is providing this opiate system to us, otherwise running would be a pretty miserable experience. Still, opiates can be very addictive. Most of us might have already encountered opiates as medication in the form of morphine or codeine. Heroin is an illegal drug that is chemically similar to morphine and every bit as addictive. I have to wonder what role the opiate system plays in people getting addicted to running. We know that there are varying levels of susceptibility to drug addiction – two people can take the same amount of drug and only one will go on to become an addict. Is the same true of highly trained runners?

IV. Conclusions

This is perhaps less of a blog post and more a collection of interesting tidbits related to running that I have come across. Still, it helps that there is a big-picture view that goes along with all of the above. The view is this: exercise is nothing short of magic when it comes to your brain. The cognitive and emotional benefits you get from strenuous exercise are virtually unmatched when compared to prescription drugs or therapy. While this post has focused primarily on the neuroscience of exercise and running, you cannot ignore the other health benefits of exercise. Heart disease is the #1 killer of men and women in America. If you don’t get up and run for your brain, then (really) do it for your heart.

The Neuroscience of Regret

Contributing blog by Melanie A. Greenberg, Ph.D.

A man is not old until regrets take the place of dreams. ~John Barrymore

We often associate regret with old age – the tragic image of an elderly person feeling regretful over opportunities forever missed. Now, groundbreaking new brain research shows how this stereotype may be true, at least for a portion of the elderly who are depressed. On the other hand, healthy aging may involve the ability to regulate regret in the brain, and move on emotionally when there is nothing more that can be done. If we can teach depressed, older people to think like their more optimistic peers, we may be able to help them let go of regret. Read on to find out how the human brain processes regret.

How Our Brains Process Regret

Studies have used functional magnetic resonance imaging (MRI) to scan the brain in real time while participants performed computer tasks that asked them to choose between different options for investing money. When participants were shown how they could have done better with alternative strategies (to prime regret), there was decreased activity in the ventral striatum, an area associated with processing rewards. There was also increased activity in the amygdala, part of the brain’s limbic system that generates immediate emotional response to threat. Interestingly, when the experiment was done with a computer making all the choices, these regret patterns were not found, suggesting that a sense of personal accountability is necessary for regret.

Do Age and Depression Affect Regret?

A new study conducted by researchers at the University Medical Center – Hamburg, in Germany provides an exciting demonstration of how healthy older people may actively disengage from regret when nothing can be done. Young people, who, presumably have more life opportunities for change and depressed elderly, who, presumably, have a deficit in emotional processing, were more regretful when confronted with missed chances for financial gain.

These researchers scanned the brains of three groups of subjects using fMRI technology: Young people with average age 25, healthy older people with average age 66, and depressed older people, also 66 on average. All participants worked on a computer game during the brain scan in which they had to decide whether to keep opening boxes or rest. Each box could contain an amount of money or could contain a devil emblem that meant they lost all their money and ended that round of the game. To prime regret, researchers showed people after each round how far they could have gone to earn more money.

There were substantial differences in brain functioning between the healthy elderly and the other groups. On both appearance of the devil and being shown lost opportunities, the young and depressed elderly showed decreased neural activity in the ventral striatum, the area associated with reward processing. The healthy elderly did not, however, show this regretful pattern when they were shown how far they could have gone; only when they actually lost all their money. Instead, when faced with their missed alternatives, this group actually showed increased neural firing in the Anterior Cingulate Cortex, an area involved in emotional regulation and control. This is a new discovery, and suggests that their brains were actively working to successfully regulate the pain of regret

Behavioral strategies differed between the groups in a way that was consistent with the brain findings. Whereas the young and depressed elderly took more risks on subsequent rounds, the healthy elderly did not change their strategies across 80 rounds on average. When participants’ physiological functioning was assessed in another similar study using the same conditions, the healthy elderly showed less increase in blood pressure and skin conductance (a measure of sweating) than the other groups. Overall, the riskier strategy did not lead to more money, suggesting that the young and depressed elderly took on extra stress for no gain.

Can Our Brains Actually Improve Their Emotional Processing With Age?

An exciting implication of this study is that brain functioning does not merely deteriorate in old age, but that aging can result in better emotion-regulation and stress management. This is consistent with other research showing old people have less intense negative emotions and are happier than middle-aged people on average.

Can Mindfulness Help?

The researchers are now working on developing interventions to help depressed people regulate regret by showing them how much chance or outside factors played a role in their choices, versus their own actions. This should result in decreased self-blame and regret.

Research on Mindfulness has also shown that Mindfulness-based interventions can increase activity and even change brain structure in the Anterior Cingulate Cortex and other midbrain regions involved in emotional processing and regulation. Mindfulness-Based Cognitive Therapy is one of the few treatments shown to be effective at treating chronic, intractable depression. Although the research has not yet been done, Mindfulness training emphasizing keeping one’s focus on the present moment and reducing self-judgment and reactivity may be an alternative and potentially even more effective way of helping depressed elderly let go of destructive and chronic regret.

Final Thoughts

In summary, regret is a negative emotion that may be adaptive if it motivates action to learn from mistakes and become a smarter or better person. However, getting stuck in regret where there is nothing that can be done to change the situation can be damaging to mind and body. For the elderly, the developmental task may be to learn to live with and accept the life they have had, focusing on the positive aspects and forgiving themselves both for mistakes made and opportunities not taken. Feeling that one has done the best one can, given the circumstances and letting go of regret can lead to self-compassion and peace.

Read my companion post about the Psychology of Regret and learn how to harness your regret to make better choices when things can be changed.

http://www.psychologytoday.com/blog/the-mindful-self-express/201205/the-psychology-regret