Neurogenesis: New Research Developments & What They Could Mean for You (Part Two)

by Melinda Burris

Last month we introduced an article that examined exciting new scientific research in neuroscience that has revealed that the brain continues generating new nerve cells or neurons on into adulthood. This new understanding has been developed based on countless research studies, and now the study of this phenomenon, neurogenesis, is a leading area of expertise in the field of neuroscience.

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This article continues to explore the groundbreaking work of Dr. Sandrine Thuret, a leading researcher in adult hippocampal neurogenesis, working from King’s College in London, where she serves as Deputy Head of the Department of Basic and Clinical Neuroscience and Chair of King’s Research Degrees Examination Board. Thuret also leads the Adult Neurogenesis & Mental Health Laboratory at the college, which serves as the epicenter for her research.¹ Part two of this article focuses on the impact of lifestyle and exercise on adult neurogenesis.

Understanding the Impact of Blocking the Adult Neurogenesis Process

Scientists now recognize that when this process of adult neuron generation is interrupted for any number of reasons from physical or mental health issues to changes in brain chemistry caused by individuals taking medications to treat serious health conditions, cognitive function, particularly memory, experiences a decline, and as a result, the individual’s quality of life decreases.²

The Effect Lifestyle Has on Facilitating or Hindering Adult Neurogenesis

Healthcare providers are constantly warning of the impact lifestyle choices have on our physical and mental wellbeing. Thuret and other neuroscientists agree that a definite link between lifestyle and the brain’s ability to create new adult-growth neurons, which occurs primarily in the hippocampus area of the brain, exists. Choosing proper diet and exercise and participating in certain activities have been demonstrated to either advance adult neurogenesis or decrease the production of these adult-growth neurons that play such a principle part in our ability to maintain our physical and mental wellbeing and slow the decline of cognitive function.

Examples of Lifestyle Choices that Either Increase or Decrease Neurogenesis

Dr. Theron outlines behaviors and activities that will increase the production of new neurons:

1. Learning
2. Sex

Behaviors and activities Dr. Theron identifies that will decrease the production of new neurons include:

1. Stress
2. Sleep deprivation—here Dr. Theron jokingly warns about balance and not taking the activity of sex, which increases new neuron generation, to such an extreme that the good it does is undermined by sleep deprivation.²

*The importance of consistent, restorative sleep has often been a topic of discussion in the pages of Hurdles First because of its profound effect on athletic performance and general good health.

Neurogenesis and Exercise

Serious investigative studies have been ongoing to better understand the links between exercise and adult neurogenesis since a pioneer in the field, Dr. Fred H. (Rusty) Gage published a groundbreaking article in a 1999 issue of Nature Neuroscience, “Running Increases Cell Proliferation and Neurogenesis in the Adult Mouse Dentate Gyrus.”²

A study published in 2009 in Hippocampus found that numerous factors can influence adult neurogenesis. Researchers placed special emphasis on voluntary exercise, asserting this type of activity “significantly increases the proliferation of hippocampal progenitors and the total number of newborn neurons.”³ Leaders of the study pointed to running as a particularly useful exercise for promoting the generation of new neurons, contending the act of running not only “increases the expression of tropic factors in the adult hippocampus, it may also promote the survival of newborn neurons, which could partially contribute to the overall increase in the numbers of newborn neurons.”³ These findings confirming the positive impact of exercise on adult neuron generation raises the question—What could this mean for professional athletes or even fitness enthusiasts who stick with a regular workout routine?

Exercise, Increased Hippocampal Neurogenesis, and the Human Brain

A 2014 scientific study investigated the possible connection between improved adult neurogenesis caused by voluntary physical exercise and the prevention of cognitive decline associated with neurodegenerative diseases including Alzheimer’s, Huntington’s, and Parkinson’s. Researchers pointed out that all conditions of this type have a common symptom—the “progressive loss of structure and/or function of neurons in the brain . . . [which causes] a more or less severe loss of certain cognitive functions including learning and memory.”⁴ Scientific evidence strongly suggests the degeneration of neurons which occurs when a person has one of these diseases, likely alters adult hippocampal neurogenesis. If proven true, this could explain why so many patients diagnosed with these conditions experience rapid cognitive decline.⁴

While the study leaders acknowledged the obvious difficulties and limitations of “direct measurement of neurogenesis in the human brain”⁴ they were successful in showing a positive link between exercise and better “performance in a neurogenesis-dependent cognitive test, the visual pattern separation task.”⁴ Using voluntary human participants, the administration of this relatively simple test provides a reliable method of measuring cognitive ability. Scientists note these results further support the theory that “adult-born new neurons [located] in the hippocampus may have a significant effect on the human brain’s ability to learn and retain memories”.⁴

While scientists still do not yet understand how exercise improves cognitive ability and aids in the prevention of cognitive decline due to aging or a diagnosis of one of the neurodegenerative diseases listed previously, the evidence that physical activity does indeed increase cognition and decreases the risk of diminished cognitive ability is clear.⁴

In her 2015 TED Talk on the ability to generate newborn-adult neurons, Dr. Theron provided other examples of research showing the importance of exercise in maintaining cognitive ability:

• Scientific studies investigating how exercise increases the ability to generate these new neurons have included comparisons between the hippocampus of a test mouse that had access to a running wheel to that of another test mouse that was not given the option of exercise. The results revealed the mouse that used the running wheel had generated significantly larger amount of new adult neurons.²

The consistent evidence demonstrated in study after study leaves no doubt that exercising regularly assists the hippocampus area of the brain (again, the section that is responsible for learning and memory) in increasing its production of these all-important newborn-adult neurons, prolonging cognitive clarity and lowering the chances of degeneration.

How Our Dietary Choices Either Increase or Decrease Neurogenesis

The importance of a proper and consistent diet regimen is also a topic that receives frequent mention in the pages of Hurdles First. This is because diet plays a major role in our health and our ability to achieve optimal athletic performance. Dr. Theron emphasizes the importance of a good dietary routine in efforts to increase the generation of adult neurons noting the following dietary choices increase neurogenesis:

1. Restricting calorie intake by 20-30%
2. Eating smaller meals throughout the day, just as you space your food intake so that you eat every few hours, or at regular intervals, when in training and particularly right before athletic competition
3. A diet rich in flavonoids (phytonutrients rich in antioxidants) such as blueberries and dark chocolate
4. Regular intake of foods rich in Omega 3 fatty acids, like salmon

Conversely, Dr. Theron pointed out several dietary choices that have been shown to decrease neurogenesis:

1. Not surprisingly, consuming large amounts of foods that are high in saturated fat decreases neurogenesis
2. Alcohol consumption has been shown to have a negative impact on neurogenesis.

However, Dr. Theron does point out that red wine drinkers may have a reason to be optimistic.² Resveratrol, a polyphenol compound believed to have properties similar to antioxidants, is found in the skins of red grapes and “has been shown to promote the survival of these new neurons.”² Meaning, the positive impact of the resveratrol may counteract the negative impact of drinking alcohol. Non-drinkers can enjoy the benefits of resveratrol by consuming peanuts and berries.⁵

3. Interestingly, there have even been a number of studies, lead primarily by Japanese researchers, about how the texture of the foods we eat either increase or decrease our rate of neurogenesis. Studies suggest a soft food diet diminishes the capacity for neurogenesis, while a diet that requires mastication (chewing) improves the rate of new adult neuron generation.²

This contention that even the texture of the foods that make up our diet can have a significant impact on our health, particularly neurogenesis and maintaining cognitive ability, is supported by findings from independent studies that have demonstrated a pronounced “impairment in learning and memory abilities” in study participants on a soft diet. This finding has led to the hypothesis that aging individuals may be more prone to cognitive decline in part because of dental weakening, a condition that progresses with the advancement in years and may limit the capacity to chew food.⁶

Summary

Time and again, science shows that our health heavily relies on how we fuel our bodies. The old adage, “You are what you eat,” is constantly being proven true by medical findings. These new and exciting discoveries about adult neurogenesis emphasize once again that it is not only what you eat, but a multitude of dietary choices that impact your wellbeing—from how often you eat, how much, what, and when. As discussed in the article, even the texture of the foods we consume, whether they require chewing or not, has been shown to have an impact on our health and the all-important ability of the brain to continue to regenerate adult-born neurons.

References

1. King’s College London. (n.d.). Sandrine Thuret, Dr. rer. nat., Biography.
2. Thuret, S. (June 2015). You Can Grow New Brain Cells: Here’s How.
3. Muotri, A.R. et al. (2009.) Environmental Influence on L1 Retrotransposons in the Adult Hippocampus.
4. Yau, S., et al. (2014). Physical Exercise-induced Adult Neurogenesis: A Good Strategy to Prevent Cognitive Decline in Neurodegenerative Diseases?
5. Web MD. (2005-2020). Resveratrol Supplements.
6. Stangl, D., & Thuret, S. (2009). Impact of Diet on Adult Hippocampal Neurogenesis.

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