Exercise – Good for Neurotransmitters & Your Brain

As the 2016 Olympic games play out in Rio, you might be feeling inspired to get moving yourself. While some sports admittedly look pretty dangerous, and we cringe at the sight of a cyclist skidding into the curb on a wet road and landing on her head, there are others that simply make us marvel at the agility and strength of the human body. For me, when I watch those swimmers cutting through the water at tremendous speed, I just want to get into a pool and see if I could really try to swim faster myself.

We’ve probably all heard by now that “sitting is the new smoking,” and that our health suffers greatly from inactivity. The human body was meant to be in motion at least for an hour or two a day, and this is known to keep the cardiovascular system tuned up as well as preventing excessive weight gain. But did you know that exercise affects levels of neurotransmitters in the body and can actually help you prevent or overcome disorders such as depression?

Depression is a Major Cause of Disability

According to the World Health Organization, an estimated 350 million people are affected by depression. This makes it the leading cause of disability worldwide, and less than half of those affected do not have access to effective treatment. More women than men suffer from depression.

Earlier attributed to a “chemical imbalance,” the causes of depression are now known to encompass multiple factors including oxidative stress, inflammation, changes in neuroactive hormones that affect nerve function and neurotrophins that control nerve growth, and altered brain volume due to changes in brain-derived neurotrophic factor (BDNF)[1].

Exercise can Prevent and Treat Depressive Disorders

Multiple studies have found that regular exercise has an antidepressant effect, but what is the biological basis for this? A recent review [1] describes the evidence showing that physical exercise reduces the oxidative stress and inflammation that can contribute to depression, and that it increases factors that are reduced in depression, including BDNF levels, hippocampal volume, brain capillarization (increasing blood supply to the brain), neuronal plasticity, telomere length, and the activity of the monoamine neurotransmitters serotonin, dopamine, and norepinephrine. Besides, exercise can simply make you feel good – that “runner’s high” feeling comes from the release of endorphins in response to exercise, which have a euphoric effect. Recently, the endocannabinoid anandamide has also been implicated in mediating the benefits of exercise on mood, contributing to a reduction in depression and anxiety [2].

Exercise Increases Neurotransmitters that are Depleted in Depressed Patients

Since physical exercise helps to keep serotonin levels high, this should not only improve mood but also help prevent depression.

Raising brain serotonin levels is the basis of SSRI (selective serotonin reuptake inhibitor) treatment for depressive disorders. Studies have shown that aerobic exercise increases serotonin concentrations, tryptophan availability, and the activity of serotonin receptors. For example, when muscles are working, they take up branched-chain amino acids (BCAAs) as fuel; these BCAAs compete with tryptophan for transport across the blood-brain barrier, and so the reduction in levels of BCAAs as they are used up by the muscles allows more tryptophan to enter the brain tissue where it is available for conversion to serotonin [2]. Since physical exercise helps to keep serotonin levels high, this should not only improve mood but also help prevent depression, and could potentially be used in therapy in place of pharmaceuticals – at least to treat mild depression [3].

Yoga Increases GABA

People with joint issues or those who have been advised by their doctors not to undertake strenuous activity can still experience the positive effects of exercise on brain health with more gentle forms of exercise such as yoga. Yoga is known for its calming effects on stress and anxiety, and brain levels of the inhibitory neurotransmitter GABA (gamma-aminobutyric acid) have been found to increase during yoga practice [4]. A study comparing yoga practice with walking, both for 60 minutes 3 times weekly for 12 weeks, found greater improvements in both mood and anxiety symptoms in the yoga group, and a brain imaging technique showed that increased levels of GABA in the thalamic area of the brain were correlated with these positive mood changes [5]. Some conditions that are exacerbated by stress such as depression, anxiety, PTSD, chronic pain, epilepsy, and mood disorders are all associated with low GABA levels and have been shown to improve using drugs that increase activity of the GABAergic system. It has therefore been suggested that regular yoga practice could benefit people with these disorders [6].

Feel Good about Exercise

You don't have to be an Olympian to feel good about exercising. Yes, it’s great to win a medal, but even some Olympians are happy simply to compete, as Eddie the Eagle exemplified. Hearing the Olympians’ stories of hard work and dedication to achieve their sporting goals is certainly inspiring, but we can all experience a little bit of that sense of achievement by just starting somewhere and setting our own goals.

We can gradually increase activity to a level where we can feel that we are really doing something to take better care of ourselves, and experience that benefit in mood and a feeling of wellbeing as the brain responds. Don’t overdo it, listen to your body (unless it’s telling you to stay on the couch) and award yourself a gold medal for effort.

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[1] Pareja-Galeano H, et al. Biological Rationale for Regular Physical Exercise as an Effective Intervention for the Prevention and Treatment of Depressive Disorders. Curr Pharm Des. 2016;22:3764-75.

[2] Heijnen S, et al. Neuromodulation of Aerobic Exercise-A Review. Front Psychol. 2016;6:1890.

[3] Young SN. How to increase serotonin in the human brain without drugs. J Psychiatry Neurosci. 2007;32:394-9.

[4] Streeter CC, et al. Yoga Asana sessions increase brain GABA levels: a pilot study. J Altern Complement Med. 2007;13:419-26.

[5] Streeter CC, et al. Effects of yoga versus walking on mood, anxiety, and brain GABA levels: a randomized controlled MRS study. J Altern Complement Med. 2010;16:1145-52.

[6] Streeter CC, et al. Effects of yoga on the autonomic nervous system, gamma-aminobutyric-acid, and allostasis in epilepsy, depression, and post-traumatic stress disorder. Med Hypotheses. 2012;78:571-9.