I have listened to many Podcasts from Found My Fitness. Dr. Rhonda Patrick has interviewed some incredible scientists over the years. Some of my favourites are Dr. Longo and Dr. Panda. Check out her website here
While emerging research continues to stack up, it’s important to note that the exact nature and extent of the role of exercise for clinical treatment of depression have yet to have been fully elucidated or agreed upon. If you believe you may have a bonafide clinical disorder, please seek out a mental health expert for proper diagnosis and clinical treatment. )
The converging evidence for the ameliorative role of exercise
There’s little debate that exercise is good for you. An abundance of scientific data demonstrates that regular moderate- to vigorous-intensity aerobic activity – whether it’s running, cycling, kickboxing, or shimmying across the dance floor – can help prevent weight gain, improve cardiovascular and metabolic health, and reduce the risk of developing cancer.
But for many people who exercise regularly, the benefits are more tangible: It simply makes them feel good. In fact, the feel-good effects of exercise may be one of the most powerful strategies available to improve a person’s mental health, whether they’re suffering from a mild case of mental funk or dealing with anxiety or major depressive symptoms.
The case for attributing causality to the role of exercise in improving mood and preventing or managing the symptoms of depression is bolstered by multiple types of converging evidence. For example, Mendelian randomization studies, which provide evidence of links between modifiable risk factors and disease based on genetic variants within a population, have found that not only are some people genetically predisposed to engage in more physical activity, but they are also less likely to suffer from depression.
Randomized controlled trials have also demonstrated that exercise may be an effective intervention for preventing or mitigating depression, especially as an adjunct treatment. Perhaps some of the most interesting findings come from mechanistic studies, which have identified the molecular mechanisms that drive the improvements in mood that accompany exercise.
On the molecular level, human studies have demonstrated that aerobic exercise can increase tryptophan transport into the brain to form serotonin, prevent the formation of the quinolinic acid neurotoxin associated with depression, cause a transient increase in immune factors that beneficially impact brain cell growth, increase in brain-derived neurotrophic factor (BDNF), and boost endocannabinoids and endorphins that evidence suggests are associated with runner’s high.
The beneficial quality exercise has within this domain seems to be especially impacted when that exercise happens to be both vigorous and aerobic. For example, evidence suggests that 40+ mins at 70-80% max HR has a high likelihood of a very strong BDNF response.
And it’s important to mention that, while aerobic exercise has been shown to help in the prevention and treatment of depression, strength training probably also has a place. Resistance exercise training has also been associated with a 45% reduction in multiple depressive symptoms according to a meta-analysis of 33 randomized controlled trials. My personal favorite flavor is indoor cycling or going on a long run, but there’s probably some flexibility in there to just find something that fires you up and go for it.
A broader overview of depression
In addition to the episode above, we’ve also just released a new 13-page review article on the website that covers much more.
This article on depression covers everything from etiology including traumatic experiences, chronic inflammation and stress, decreased neurogenesis in the brain, disrupted circadian rhythm, gut microbiome dysbiosis, genetic predisposition and more. It also covers some emerging treatments including pharmacologic, exercise, diet, sauna use, omega-3 fatty acids, probiotics, light therapy, meditation, psychedelics, and transcranial direct current stimulation.
Neuroplasticity in depression
One particularly interesting point covered in the depression topic page is the role that neurogenesis (the growth of new neurons) plays in both the etiology and treatment of depression. Disrupted neurogenesis and subsequent connectivity losses or failures have been implicated in depression. This leads to a decrease in neuroplasticity, which is the brain’s ability to reorganize and remodel itself based on experiences, behaviors, and genes by forming new neural connections throughout life. Neuroplasticity is disrupted in depression and other mental health disorders and this has been shown to play a significant role in the onset and development of depression.
One of the most powerful growth factors produced in the brain called brain-derived growth factor (BDNF) has been shown to play a major role in increasing both neurogenesis and neuroplasticity. Reductions in plasma and serum levels of BDNF have been found in people with depression. Stress and other factors can reduce BDNF, whereas exercise consistently increases serum BDNF, which can cross the blood-brain barrier and have beneficial effects in the brain. For example, moderate to intense aerobic exercise for 40 minutes caused an average ~ 32% increase in serum BDNF levels compared to baseline levels.