Using targeted exercise for stimulating neurogenesis, to grow new brain cells.
In the previous article we discussed neurogenesis, where it occurs in the brain and the amazing observation that we can stimulate this process through our diet, lifestyle, and behaviors. Before we discuss stimulating neurogenesis with exercise, let’s review some neurogenesis concepts.
What is Neurogenesis?
Neurogenesis is the body’s innate ability to grow new brain cells, new neurons in the adult human brain. Neurogenesis is a type of brain plasticity and plays a part in reducing the degenerative effects that aging has on the brain. The degree to which neurogenesis can occur is dependent on your genetic blueprint and your environmental conditions (state of health and activity). Understanding neurogenesis lays the foundation to explore potentials for increasing brain function, health, anti-aging, and reducing cognitive decline.
Neurogenesis occurs in the hippocampus more than any other region in the brain
The hippocampus is a curvy seahorse shaped structure of the brain. It is located in a region called the limbic system, which is responsible for behavior and emotional responses. Within the limbic system, the hippocampus is responsible for the functions of learning and memory- forming episodic and spatial-navigational memory in particular. As part of its memory functions, it links to the conscious mind in ways such that senses like smell or taste can evoke a memory from the past. The hippocampus is the primary site of neurogenesis in the brain. How interesting, that the site of learning in the brain is also the site of new brain cell growth!
BDNF stimulates the neurogenic process
Brain Derived Neurotrophic Factor or BDNF for short is a neurotrophin that plays a crucial role in the survival and differentiation of neurons during their development as well as the creation of new neurons. BDNF is found in brain regions such as the hippocampus, amygdala, cerebellum, cerebral cortex as well as organs such as the heart, liver and lungs. The highest concentrations of BDNF are found in the hippocampus.1 BDNF can be viewed as a fertilizer that stimulates neurogenesis. Therefore, factors that stimulate BDNF increase neurogenesis. One of which is exercise.
Exercise increases neurogenesis…. but how
We have known for a long time that exercise improves mood, cognitive function, enhances memory, and learning capability.2 It has even been shown to have antidepressant effects and protect against age related cognitive degeneration such as that seen in dementia and Alzheimer’s.3 This is because physical training increases angiogenesis (new vascular formations), synaptogenesis (new neuronal connectivity)4,5 and hippocampal neurogenesis which improves learning capacity.6
Exercise’s effect on neurogenesis occurs because exercised peripheral muscles secrete proteins and other metabolic derivatives into the blood stream. Those materials function as messengers; they cross the blood brain barrier and mediate BDNF function in the hippocampus and other brain regions.7
Regular aerobic exercise is best
Exercising to stimulate neurogenesis may be as simple as getting on a mouse wheel. A 2005 study8 showed that older age mice placed on a running wheel showed faster acquisition and memory retention in maze tasks after only 1 month of exercise compared to younger non-exercising mice. An even more stunning observation was that the rate of neurogenic decline in aged mice that ran on a wheel for 1 month was reversed by 50%. The same principles apply to us- probably because modern life is a rat race… sorry bad joke.
Humans, similar to mice, have a dose dependent relationship between exercise and BDNF stimulation and expression. Regular aerobic exercise of a moderate nature increases the magnitude of BDNF expression following each workout session.9 In fact, Erickson et al. 2011 found that exercise increases the size of the hippocampus in human adults.10
The greater the regularity of exercise, the higher the consistency of BDNF stimulation and enhanced brain function.
Extreme exercise can disrupt BDNF and Neurogenesis
Extreme exercise has been shown to disrupt and impair metabolic, endocrine and cognitive functions in humans. This is theoretically due to the high production of reactive oxygen species (ROS) that leads to cellular mortality. In other words, exhaustion level training diminishes vitality and with it, neurogenesis.
The research ironically does not define extreme exercise. It does however address acute exercise. All training causes some level of ROS production and release in the body. In regular training, the ROS production is mitigated by free radical scavenging activity following the exercise. This is an adaptive or hormetic response and promotes regular recovery. Acute or irregular training does not involve that same adaptive response.11
Extreme exercise could be interpreted as “regularly training to exhaustion” with triathlons, Iron Man, ultras and other high endurance level type systems. Targeted nutrition for those types of athletes is therefore crucial for replenishing nutrients and mitigating long term impact.
Strength training programs with weights have not shown significant positive BDNF expression.12 Variations in the number of reps and weight lifted compared to 1 rep max size has been shown to influence the reactive oxygen species (ROS) production. Lifting moderate size weights in a regular training program demonstrates less of an inflammatory response.13
Considering those findings, I do find strength training to be an integral part of any healthy regimen, and the best training program is a varied one that always changes and incorporates new challenges.
Moderate exercise for neurogenesis
Moderate levels of exercise on the other hand have a strengthening effect on the immune system and antioxidant defense system. Moderate aerobic exercise clearly stimulates neurogenesis via BDNF as represented in the current research.7 The clearest indication of moderate exercise has been regular treadmill use.14 Additionally, regular refers to at least 3 times a week.
Thus, one can qualify regular moderate running, swimming, treadmill use within the “moderate” aerobic exercise category for stimulating neurogenesis. They should be included as part of a weekly exercise or fitness regimen. My recommendation regarding strength training is to continue- most forms of training have a benefit albeit varied. Even though strength training does not stimulate BDNF, its benefits are extensive.
Food for thought
The hippocampus is responsible for learning and is the primary site of neurogenesis. Regular aerobic exercise stimulates new brain cell production. General learning and especially challenging or novel tasks stimulate new brain pathways.
With that in mind, what double task training would you do? Exercise and a new language? Exercise and self-talk/mental reconditioning? Exercise and overcoming fear? Exercise and balance? Even exercise and fun…
How would you apply this information to bring greater meaning to your life and your loved ones?
Disclaimer. The information represented in this article is meant to provide concepts from evidence based research. It is not intended to treat or diagnose any health condition. For appropriate treatment methods please contact your healthcare provider.
