Neurogenesis: New Research Developments & What They Could Mean for You

By Melinda Burris

This article explores exciting new research in the field of neuroscience and findings that demonstrate that despite earlier beliefs of the medical community to the contrary, the adult brain continues to produce new nerve cells called neurons. This process is known as neurogenesis and recent studies showing links between regular exercise, proper diet, and a quality sleep routine as well as neurogenesis and depression, are game-changers in validating the importance of making good lifestyle choices not only to enable elite athletes to perform to the best of their ability for as long as possible, but also to avoid cognitive decline, other adverse effects of aging, and potentially avoiding or mitigating the risks of neurodegenerative diseases including Alzheimer’s and Parkinson’s.
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Dr. Sandrine Thuret

Dr. Sandrine Thuret, one of the world’s foremost neuroscientists, specializes in Adult Neurogenesis, leading the department dedicated to this field of study at King’s College in London as well as the school’s Mental Health Laboratory. The endeavors of the department’s laboratory focus on adult hippocampal neurogenesis. The hippocampus area of the brain is instrumental in memory creation and regulation of mood.¹

Thuret’s scientific research is centered on how adult-born neurons are produced and how an individual’s environment, as well as the cellular processes involved in the generation of adult-born neurons, affect major aspects of the human condition including mental health (depression), the normal aging process, and patients diagnosed with a range of disease states from cancers to Alzheimer’s and depression.¹

Dr. Thuret’s TEDTALK in London—June 2015

Thuret brought international attention to the scientific research that has taken place over the last 16 years into adult-grown neurons and the hope that continued study into neurogenesis holds for successfully predicting and developing proactive treatment strategies for these all too common neurodegenerative diseases at a TEDTALK she delivered in London in June 2015.

Thuret opened her presentation, “You Can Grow New Brain Cells: Here’s How” by posing the following question: “Can we, as adults, grow new nerve cells?” While the doctor answered her own question with an unequivocal, “Yes, we can,” she also acknowledged that confusion and division still exists among experts on this topic because this is such a new area of research.²

As a personal anecdote, Thuret relayed the surprised reaction of one of her professional colleagues, an oncologist named Robert, when she first explained neurogenesis to him. Their conversation began with Robert expressing to the speaker how confusing and difficult to understand he found it to be when a large number of his patients, despite being informed their cancer treatment had been successful and the disease was no longer detectable in their system, still presented with symptoms of depression—a fact he found hard to reconcile with the joyous news of their remission and what he expected their natural reaction to be. From his perspective, their continued depression seemed at odds with the reality of their improved health and the best possible prognosis he had just given them.²

In contrast, Thuret remarked, “Well, from my point of view, that makes sense . . . the drug you give to your patients that stops the cancer cells multiplying also stops the newborn neurons being generated in their brain.”²

The oncologist replied, perhaps predictably, “these are adult patients; adults do not grow new nerve cells.”² Robert was taken aback when Thuret responded, “Well, actually we do; and this is a phenomenon that we call neurogenesis.” Wanting to learn more, Robert arranged to visit with Thuret at the Mental Health Laboratory, King’s College, London, where Thuret’s research is based.

Their time together at the laboratory focused primarily on the hippocampus, which Thuret describes as the “most exciting part of the brain when it comes to neurogenesis.”² As Thuret points out, “What medical experts have long known is that the hippocampus is the portion of the brain that is important for learning and memory and mood and emotion . . . what we have learned more recently is that this is one of the unique structures of the adult brain where new neurons can be generated.”²

Research from the University of Queensland backs up Thuret’s assertions, noting that while neurogenesis is a critical part of brain development in embryos, we now know that the process of neurogenesis “continues in certain brain regions after birth and throughout our lifespan.”³ In fact, the University of Queensland’s findings details why the hippocampus region of the brain is so central to neurogenesis, observing the hippocampus “alone has at least 27 different types of neurons.”³

Thuret noted a colleague at the Karolinska Institute of Neuroscience has estimated the hippocampus generates 700 new neurons each day.² While that may not seem like a lot when you consider there are billions of neurons in the human brain, the next statistic Thuret shares should give you pause:

By the time we will turn 50, we will all have exchanged all of the neurons we were born with in that structure with adult-born neurons.²

Why Are New Neurons Important and What Do They Do?

As noted previously, the neurons in the hippocampus are essential for learning and memory. Thuret’s research has demonstrated that if the brain is blocked from generating these adult-growth neurons, memory capabilities are impaired, particularly those related to spatial recognition.² Degraded spatial recognition makes it difficult for you to navigate your way, to judge space relationships correctly, and to tell your left from your right. In short, it can make accomplishing simple, daily tasks incredibly taxing.

• When memory capabilities are impaired due to lack of adult neurogenesis, our memories become jumbled.² For instance, you may park your car in the same lot every day, but if your hippocampus is not creating these new neurons, you will have difficulty locating your automobile because your ability to differentiate all your past memories of parking in that same lot from your most recent memory is impaired.

Neurogenesis and Depression

In recent decades, we have witnessed a worldwide change in perspective toward depression and a new understanding that it is a mental illness. Given his experiences with his patients who remained depressed even after being told they had achieved remission, Robert, Thuret’s oncologist colleague, was especially interested in any insights studies into neurogenesis had to offer about depression.²

Thuret’s research has revealed that individuals with depression have a slower rate of neurogenesis. It has been shown that administering antidepressants to these patients is effective in not only alleviating the symptoms of depression but also in accelerating the generation of new adult-neurons. These results, according to Thuret, “[establish] a clear link between neurogenesis and depression; but moreover, if you just block neurogenesis, then you block the efficacy of the antidepressant.”²

Therefore, it stands to reason that patients with depression, such as Robert’s who had been fighting a cancer battle, would not immediately rebound from their depressed state because the very medications that had been successful in treating the cancer had inhibited the growth of these crucial new neurons. For the brain to recover and return to its normal state, these patients require sufficient time for the neurogenesis process to begin again and allow them to regain functionality.²

Neurogenesis: “A Target of Choice”

Based on the evidence collected through her own research and the investigative studies of neuroscientists around the world, Thuret states the medical community now believes enough credible evidence has been gathered to judge neurogenesis as “a target of choice”—a method of predicting and proactively preventing and treating cognitive decline in memory formation, or mood, even when the decline is stress or age-induced.²

Thuret envisions future applications of neurogenesis taking the forms of using the information that can be gathered with this knowledge to prescribe preventative and pharmacological interventions and developing neurogenesis science so that the process can be used as a biomarker to successfully predict onset and progression of disease states. ²

As we hear repeatedly from healthcare professionals, Thuret asserts the science demonstrates there is a definite connection between lifestyle and the ability of the brain, specifically the hippocampus, to properly produce the new, adult-growth neurons that are vital to our continued ability to function at our best, both physically and mentally.

In our next issue, we will discuss Thuret’s findings that diet, not just what we eat, but how much of it, and when, are major factors in our brain’s ability to generate these new neurons. It should come as no surprise that regular exercise and consistently getting enough sleep play key roles as well. The companion article will also explore additional studies that support Thuret’s assertions about the importance of good lifestyle choices and remaining active and fit. It will also discuss ways athletes who want to stay in optimum shape for as long as possible and use preventative measures to avoid cognitive decline, can apply these findings.

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. The University of Queensland. (18 May 2017). What is Neurogenesis?

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