Exercise can help the brain fight depression, and this isn’t exactly new information. The fact that exercise can play a role in helping to both prevent and treat depression has been known for some time. But exactly how exercise works to fight depression in the brain, on a neurobiological level, hasn’t been well understood — largely because science doesn’t fully understand depression itself on a neurobiological level.
A study from the Department of Neuroscience at the Karolinka Institutet in Sweden shows the actual biological mechanism through which physical exercise protects the body from depression induced by the accumulation of stress.
Protein Linked to Exercise May Also Protect Mental Health
The researchers were able to identify a connection between a protein known as PGC-1a1 and biochemical changes that protect the brain from stress-related damage. PGC-1a1 is known to multiply in skeletal muscle when an animal exercises and helps to regulate the development of new muscle.
For a period of five weeks, the Karolinka researchers subjected groups of mice to moderately stressful conditions, including loud noises, flashing lights and the disruption of circadian rhythms. One group of mice had been genetically modified to have high levels of PGC-1a1 in their skeletal muscle, while a group of control mice had unmodified levels of the protein.
By the end of the five weeks under these stressful conditions, the group of mice with normal levels of the PGC-1a1 protein in their skeletal tissue showed symptoms of depression. In contrast, the mice with modified levels (similar to the levels that would be seen in well-trained muscles) did not display any symptoms of depression.
Exercise Prevents Stress Damage by Purging Harmful Substances
A substance called kynurenine, which is formed during times of stress, has been found in high levels in patients suffering form mental illness. However, when kynurenine is transformed into kynurenic acid, it is unable to cross the blood-brain barrier to affect a person’s mental health. This transformation takes place thanks to an enzyme known as KAT.
The Swedish researchers found that the mice that had been modified to have high levels of the PGC-1a1 protein also showed high levels of KAT. When they directly injected the modified mice and the control mice with kynurenine, the genetically modified mice did not show any symptoms of depression but the normal mice did show symptoms.
New Possibilities for Depression Treatment
Exercise is almost always recommended for patients with depression. However, the lack of energy and lack of motivation that are classic symptoms of depression can make it extremely difficult for patients to put this advice into practice, particularly if they aren’t already regular exercisers.
These new findings suggest a possible alternative approach to pharmacological treatment for depression. Current drugs used to treat depression target chemistry directly in the brain. However, this research suggests that it may be possible to treat and protect against depression by targeting skeletal muscle rather than the brain. This could give patients the mental health-related benefits offered by vigorous and regular exercise without the exercise itself.
There are many other health benefits afforded by exercise, and ideally patients would reach a stage of their recovery during which they are able to commence or resume regular exercise. But in the meantime, these results could offer another useful tool to help treat the estimated 350 million people worldwide who are believed to suffer from depression. High kynurenine levels have also been found in people with other forms of mental illness, suggesting that such an approach may be able to benefit other types of patients as well.
By: Christi van Eyken