Influencing Neurogenesis Part 1

 

Up until around 10 years ago, we believed that after childhood our brains could never form new neurons. We were allegedly stuck with a brain that wasn’t able to regenerate, would be in a steady state of decline and any attempts to change or alter that would prove to be futile. This is of course bad news for those who are worried about brain ageing, who have had a stroke, suffer from various forms of mental illness or degenerative brain disorders. In fact, this is bad news for anyone who possesses a brain. 

Alas, all is not as grim as it sounds. In fact, science now debunks this archaic suggestion. It is now fully accepted that, as adults, our brain can grow and change in response to stimulus and we can grow new neurons. So those with brains can now relax a little more.

This is thanks to a phenomenon known as Neurogenesis, as previously mentioned, the ability of the adult brain to generate new brain cells. Until the process of generating new neurons was discovered in the 1990s, scientists acted under the doctrine established in the late 19th to early 20th century by the Spanish neuroscientist, histologist and pathologist Santiago Ramon y Cajal. 

Cajal is referred to as the pioneer of modern neuroscience and when referencing the progression of adult neurons famously stated that ‘everything may die, nothing may be regenerated’. Since then it is accepted that neurogenesis is a process that occurs in the healthy brain. 

Why is this significant?

The brain is the most complex and fascinating entity in the known universe, in-fact neuroscience is effectively the brains attempt to discover itself. Despite this, we actually know very little about the brain, so therefore it shouldn’t be surprising that new science about the brain constantly evolves what we think we know about the brain, about ourselves, our personalities, mood and potential for change. 

A similar situation can be seen with regards to how we used to look at our genes. Until the established understanding of epigenetics was widespread we were considered to be a slave to our genetic predispositions. The study of epigenetics dictates that signals from our environment control how our genes are expressed.  An obvious example would be an individual who was genetically predisposed to carrying more body fat altering their body composition through diet and exercise regimes. Through environmental factors, it is no surprise we can increase or reduce our likelihood of certain genetically predisposed diseases such as certain cancers, mental health issues etc. Epigenetics shows us that we are not always victims of our genes and we can change our response to life and the environment. We can look at neurogenesis in the same way. We are not a slave to our current state of mind. It would appear that scientists love a good paradigm shift. These are not the first and won’t be the last.

Buddhist philosophy suggests that life is in constant flux and the nature of everything in life is change. Try telling that to Ramon y Cajal.. Well.. now we aim to prove that our bodies and brains are subject to constant adaptation.

This highlights our capacity to learn a whole host of new information, repair degenerative brain disease and recover from depression and other types of mental illness. The term Neuroplasticity is commonly used to indicate the malleable nature of the brain. The growth of new ideas and perspectives show us that our goopy lump of grey matter can be constantly growing, changing and adapting. Although care should be taken to provide the brain with the right conditions in which to optimize this process. 

Emerging from the darkness

In animal models of depression, we can observe that subjects have a lower level of neurogenesis. It can be observed that after administering antidepressants, there can be an increase in production of serotonergic neurons (neurons that produce serotonin) leading to reduced symptoms of depression. However, if we can block/reduce neurogenesis, we block the efficacy of the antidepressant. We can deduce that neurogenesis is a poignant target for improving memory formation and mood. This could potentially allow freedom from endless negative rumination, changing perspectives on traumatic life events, allowing us to ‘grow’ a new frame of mind and break the patterns that perpetuate our mood disorders. 

Biological observations and approaches to mental health issues are often viewed as reductive. Its almost insulting that we can be told that our neurotic intricacies and the tumultuous apoplexy of negative emotional torture could be reduced to such simple terms. That the highly personalised spoken word poetry of pure terror spewed out the mouth of our demons could be fixed by taking pills, throwing on our running shoes or eating fewer cheeseburgers.  However, studies into neurogenesis can provide us with a framework for effective treatments for mental health issues, providing personalised treatment and a more hopeful, tentative and holistic approach.

New neurons can be generated in the hippocampus, a grey structure in the brain that is important for learning, memory, mood and emotion. Studies have shown that neurogenesis in this area of the brain has increased ability for spatial recognition and recall such as: Navigating your way around a city, remembering routes home or remembering where you left your bloody bike locked up after a long day at work!

This process can also work in the opposite direction. It is well understood that prolonged or intense stress can cause physiologically deleterious effects on the brain. These effects, which are often particularly pronounced in the hippocampus include atrophy of neurons, neurotoxicity and a condition known as neuro-endangerment: where neurons are more susceptible to further insult. This shows how much stress becomes a vicious cycle of feedback whereby increased or chronic stress over time damages our ability to cope with stress and so forth.

Stress, sleep deprivation, alcohol consumption, and other factors can reduce neurogenesis, it also declines with age. It is therefore important to actively regulate stress in your life and maintain positive sleep hygiene in order to ensure we can avoid reducing neurogenesis and ending up in negative, maladaptive patterns of behavior that feed off one another. 

But can we make changes to our lifestyle to benefit our rate of neurogenesis? Absolutely.

Focused learning, good sleep hygiene, reducing stress, sex (albeit not too much to cause sleep deprivation), intermittent fasting, exercise and diet can play a huge role in increasing neurogenesis. 

Part 2 of this article takes a deep dive into the influence exercise and specific dietary interventions can have on neurogenesis and brain health. 

Check out ‘Influencing Neurogenesis Part 2: Exercise, BDNF, fats & blueberries‘ for more!