*Brianne Kent [2011] is doing a PhD in Experimental Psychology
When it comes to the brain, it seems that bigger is better. Neurogenesis is the term scientists use to refer to the production of new brain cells, called 'neurons'. It was once thought that neurogenesis only occurred prenatally, such that you were born with all of the brain cells that you would ever have. However, since the 1980s there has been growing consensus that a few specific regions of the brain continue to produce new brain cells throughout life, a process known as 'adult neurogenesis.' Importantly, several healthy lifestyle choices centred on diet and exercise can increase this mechanism and appear to benefit the mind.
Although the purpose of these new neurons is not yet fully understood, a portion of these cells appear to become functionally integrated into areas of the brain essential for learning and memory processes. Some researchers hypothesise that young neurons increase the amount of storage space for memories, while others believe that these cells improve the storage mechanism for 'encoding' information, in such a way that memories are more accurately and easily remembered.
Adult neurogenesis has been demonstrated in several animal species, including rodents, birds, monkeys and humans. Manipulating neurogenesis by pharmacologically inhibiting the production of new brain cells or alternatively by using treatments to promote production has been shown to directly affect the cognitive performance of several species. For example, mice and rats with reduced neurogenesis have difficulty with spatial navigation, recognising a previously encountered object and drawing associations between events that are separated by a time delay, analogous to the causal link between lightening and thunder. All of these cognitive processes rely on an area of the brain called the 'hippocampus', which is one of the regions where neurogenesis continues into adulthood, and is often thought of as the memory centre of the brain.
In humans, reductions in neurogenesis may contribute to conditions such as depression and Alzheimer's disease. It is hypothesised that increased neurogenesis may underlie the benefits of anti-depressant medication that improve mood and several treatments designed to help patients suffering from memory loss. Luckily, there are several easy ways to increase the production of new brain cells and to protect the ones you have.
The most effective ways to enhance neurogenesis include exercise and eating less. Providing mice with running wheels doubles the number of new neurons that their brains produce. Similarly, humans participating in aerobic exercise a few times each week show patterns of brain activity suggestive of increased cell production. Importantly, in both mice and humans, exercise induced neurogenesis is associated with improved cognitive performance. These beneficial effects of exercise on neurogenesis and cognition are also seen when daily food consumption is reduced. In rodents and humans, reducing food intake by 30% each day has been shown to increase cell production and improve memory in just a few months.
It is also important to acknowledge that not all new brain cells survive long enough to become functionally integrated and useful. Fortunately, there are other behaviours, along with exercise and restricting food consumption that increase the survival of brain cells. These beneficial behaviours include reducing stress levels, getting sufficient sleep and continuing to actively engage your mind through new experiences and education. All of these behaviours protect brain cells and prevent age-related memory loss, while also having countless benefits on overall health.
If you needed one more reason to live a healthy lifestyle, know that by eating well and exercising, you will be helping to grow your brain.