Running: A Free and Natural Antidepressant

Running, Ancient Era, Evolution and Children

Running has been always one of the preferred aerobic exercises chosen by all the age categories. One interesting point is that basically this type of motion come from the ancient era when escape from harmful environment or threats was of crucial importance. Another factor that shows up and makes running an instinctive and natural characteristic is in childhood, almost all children are in running-mode, they run while playing, but it is also in ther mood. Running for them is a lifestyle to discover as fast as possible each detail in their surrounding environment.

For the purpose of a healthy neuronal development and increased metabolism, children have to use various kind of movements of different degree.

Recently, running has been associated with antidepressant effects. We all know the benefits running can give. From bone and muscle strengthening to lowered risk of cardiovascular diseases and diabetes, this kind of aerobic exercise is one of the most convenient and efficient methods to ease everyday stress and raise quality of life.

What should we know about antidepressant effects of running?

Running has been studied on an extensive field. Some of the core hormones and neurotransmitters involved in coordination of running and its aftereffects have been questioned. Their importance already possess an analogy with learning and memory, sleep-wake cycle, stress and depression.

Picture showing the location of Hippocampus inside the brain's limbic system.
Picture showing the location of Hippocampus inside the brain's limbic system.
  • Hippocampus is a part of the brain responsible for consolidation of long and short-term memory. This region also plays an important role in stress and depression.
  • Brain Derived Neurotrophic Factor (BDNF) is a special protein - or neurotrophin - responsible for growth of new neurons, survival and neuronal plasticity inside the central nervous system. Being a new trend in science, increased BDNF level is thought to have strong correlations to the degree of physical activity, and has a strong connection with memory, learning and neurological diseases.
  • Dynorphin is an opiate derivative, it acts as a two-edged sword inside the brain's reward system. It is highly researched because of role in drug seeking behaviour.

  • Flinders Sensitive Line rats are genetically modified rats in order to produce behavioral responses similar to those noticed in depression. Flinders Resistant Line are usually the control group with no previous laboratory manipulations.

My Memory and Thinking Has Improved Since I've Started Running Almost Every Day

Most people report sudden improvement in cognitive skills even after a jogging session of circa 20-30 minutes, and a long lasting increase in learning skills over an extended course of training sessions. Much attention has been given to a particular protein called Brain Derived Neurotrophic Factor. BDNF is a major coordinator in brain cell survival, formation of new synapses and neuroplasticity. These beneficial characteristics are strongly correlated with the degree the human mind can learn, memorize and generally, think.

Several studies have demonstrated elevated levels of BDNF after exercise in humans. Abnormal levels of BDNF are also associated with mental illnesses like schizophrenia, depression, obsessive-compulsive disorder (OCD) and neurodegenerative diseases like Alzheimer's disease and Huntington's Chorea.

Brain Derived Neurotrophic Factor (BDNF), Hippocampus and Cell Proliferation

Two groups of mice were set to do exercise tasks on wheel. Scientist measured the level of BDNF and dynorphin in order to assess the level of depression and its changes over a 5 week course of continuous wheel-running and forced swim tests.

The groups were subdivided into Flinders Sensitive Line (FSL) and Flinders Resistant Line (FRL). During the experiment, the results showed a decrease in depressive symptoms in FSL group while the levels of BDNF and dynorphin remained unaffected in both groups. Even after 5 weeks FRL group showed increased BDNF and dynorphin levels in contrast with lower ones in FSL, the level of hippocampal cell proliferation was greater in “depressed” rats than the control group.
This means BDNF and dynorphin levels seem to be independent from the current mental status, being depressed certainly carries the thought of climbing a second step to feel better. Hence, FSL group of 'depressed' rats showed greater cell proliferation.

Neurotrophic Hypothesis of Depression

Translated into a real-life example, this study gives a clear insight that running certainly help in alleviating symptoms of depression and the genesis of new cells inside the hippocampus - above all associated with learning and memory - may possess a connection between cognitive impairments in depression.

Another study reinforced the evidence by pointing out the time dependency of running, however the degree of running related to BDNF mRNA expression did not showed a significant correlation.

 
FSL group
FRL group
Before 5th week
 
 
Hippocampal cell proliferation
Increased
No increase
BDNF/dynorphin levels
Same as FRL
Same as FSL
At 5th week
 
 
Hippocampal cell proliferation
Increased
No Increase
BDNF/dynorphin levels
Increased but not significantly
Increased

Raphe Nuclei

Some of the 5-HT System's receptors and proteins

  • 5-HTT or SERT is a membrane protein responsible for transportation of serotonine. This transporter is one of the main targets in antidepressant research.
  • 5-HT1a receptor is the most abundant and widespread of all the 5-HT receptors. Its activation is mainly associated with various positive behavioral responses to environmental impulses like increased sociability and decreased aggression. 5-HT1a is located in several brain regions like hippocampus, striatum, amygdala and cerebral cortex.

Since I Started Running I Feel Like I'm Coping Better With Stress

A very useful scientific approach is making big efforts to understand and underpin the secrets of the role of serotonin. Serotonin is an important neurotansmitter mainly involved in cognitive skills, memory processing, sleep and mood regulation.

A huge scientific literature support the idea that this monoamine neurotransmitter, if synthetized abnormally, can contribute to development of mental illnesses, conitive impairments, sleep and personality or behavioral disorders. On the other hand, serotonin, or the 5-HT system can be regulated by doing regular activity, moreover few receptors cooperating with serotonin system undergo beneficial changes right after a physical activity is finished.

Resistance to Stress, Stress Control, Raphe Nuclei and 5-HT System

In study made by Greenwood et al suggested the examination of a specific portion of the brainstem, the raphe nuclei. The study was performed with 37 adult Fischer rats. These animals were then subdivided into sedentary lifestyle, 3-week and 6-week voluntary access to running-wheel.

The scope was to examine few of the 5-HT receptor family, from these: 5-HTT, 5-HT1a, 5-HT1b and Alpha-1B adrenergic receptor mRNAs were put under analysis. The specimens were extracted from dorsal, ventral and medial parts of raphe nuclei. The results showed a time-dependent change in these receptors pointing out the relevancy of stress relief, antidepressant and anxiolytic properties.

The results showed different levels of mRNA expression according to rate of physical activity and receptor type. What has become evident, is that receptor changes occurred in different manner, however the overall profile clarifies the evidence of antidepressant effects of running.

  • Anandamide, also known as N-arachidonoylethanolamide or AEA is a cannabinoid neurotransmitter mainly known for regulation of appetite, sleep and pain relief.
  • 2-Arachidonoylglycerol (2-AG) is also an endocannabinoid agonist of CB1 receptor. It is thought to have potent neuroprotective properties.

I Feel Happy After and Even During Running

If we decide to run a few miles physically untrained, bad feelings like the desire to stop for a break or suffering because of high demands from the instructor - if we apply for a training program -, and above all the difficult path and mental status that we have to overcome in order to reach the end of our running track can lower your performance.

It is very interesting that during every kind of physical exertion, we experience at some point a feeling of euphoria or mental high that may give us more energy to continue the activity. This is a well-known term called runner's high.

Runner's high and the "Opioid Theory"

In a study ten athletes were set to perform endurance running for 2 hours. After that, their brains were examined with fmri scanning technique. Results showed that specific binding of opioid receptors and reduction of opioid receptors were correlated to increase in euphoric mental states after running. This clearly shows that overcoming our pain threshold significantly produces effects of happiness with the purpose of continuing the activity.

Running and The Endocannabinoid System

Another study showed a strong connection with endocannabinoid neurotransmitter level and exercise. The study measured two of the most important endocannabinoids, anandamide and 2-AG. The level changes were examined on three taxons such as humans, dogs and ferrets. The scope was to estabilish a positive correlation between pre- and post-exercise endocannabinoid levels.

Humans had significanty higher levels of these neurotransmitters, indicating an evidence of elevated mood and brain function.

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