We all know that children’s brains grow and expand as they learn and age. Adults, on the other hand, slowly begin to lose brain cells and matter as they get older. That’s because cells begin to die before your body has a chance to repair them. In fact, until as recently as the 1990s, it was thought that once brain cells die, no new cells are created to replace them. We now know that this isn’t the case.
Neurogenesis in Adults
Research has proven that it is possible for adults to grow new brain cells, so how does it happen?
A 2002 report in The Journal of Neuroscience begins:
“A milestone is marked in our understanding of the brain with the recent acceptance, contrary to early dogma, that the adult nervous system can generate new neurons. One could wonder how this dogma originally came about, particularly because all organisms have some cells that continue to divide, adding to the size of the organism and repairing damage.” (1)
The formation of new cells in the brain (and the rest of the central nervous system) is called “neurogenesis”. Recent research into neurogenesis has built on the findings of Joseph Altman in 1962, which was previously largely ignored. Altman found that new neurons form even in adult rats, contradicting conventional wisdom that neurons develop in babies and children only until the end of adolescence. (2) Science has since proven that neurogenesis occurs in adult humans as well. (3, 4)
An Ever-Changing Brain
The concept of neuroplasticity is based on Altman’s work, suggesting that the brain never stops growing and learning.
Neurogenesis works by creating new neurons from stem cells in the hippocampus (responsible for memory storage and cognition), subventricular zone (where stem cells are created and proliferate to connect to other regions of the brain) and olfactory bulb. (5, 6)
This is very good news, not only in the context of diseases such as Alzheimer’s and Parkinson’s but for the maintenance of optimal brain health and the prevention of such neurodegenerative disease. It can also improve depression and other mood disorders.
“The turning point of the collective perception about neurogenesis occurred with the demonstration that adult mammalian brain neurons are also capable of mitosis, and that newborn neurons can migrate and integrate into existing circuitries.” (7)
So you can, in fact, teach an old dog new tricks.
Growing Your Brain
Your brain will produce new neurons on its own but there are things you can do to facilitate the process.
Here’s how to keep your brain in optimal shape:
Exercise – regular exercise benefits not only your muscles and bones but your brain as well. Exercise increases the volume of blood delivered to the brain, stimulating the subventricular zone to create new neurons. (8) Furthermore, the increased blood circulation in the brain caused by aerobic exercise increases the volume of the hippocampus, which often shrinks as we get older. Something as simple as walking for 45 minutes a day has been shown to increase hippocampus size. (9)
Intermittent Fasting – the concept of conscious fasting is relatively new in health circles. By abstaining from food for extended periods, our bodies go into survival mode and cells that would ordinarily die remain active, extending their lives. (10) Additionally, fasting promotes autophagy (i.e., the brain’s sanitation system) to remove toxins that accumulate in surrounding fluid and tissues. (11)
Stress Reduction – chronic stress causes a host of problems for the body, one of which is the restriction of hippocampal neurogenesis. Since the production of new neurons in the hippocampus modulates certain neurotransmitters that contribute to mood and depression, reducing emotional and mental stress can improve symptoms of anxiety and depression. (12) You can find some suggestions for reducing stress here.
Diet – certain foods are known to promote neurogenesis, such as:
- Green tea: polyphenols are a particular type of antioxidant. One polyphenol is epigallocatechin-3-gallate (EGCG); it’s found in green tea and known to enhance adult neurogenesis in the hippocampus. (13)
- Turmeric: found to improve neuroplasticity, cognition, memory, and hippocampal neurogenesis (14, 15)
- Blueberries and raw cocoa: the flavonoid antioxidants in these and other fruits and vegetables contribute to neurogenesis in the hippocampus. (16)
- Omega-3 fatty acids: the brain depends on DHA (docosahexaenoic acid) fat for normal signalling and function. Most Western diets don’t include enough of it. (17, 18) Sufficient levels of omega-3 fatty acids results in the prevention of shrinkage of the hippocampus. Dietary sources include fatty fish (e.g., mackerel, salmon, oysters, herring, caviar, anchovies); nuts and seeds; and fish oil supplements.
- Avoid sugar: refined sugars affect proteins and neurotransmitters in the brain responsible for learning and memory.
Can Your Brain Grow Too Much?
Is there such a thing as too much neurogenesis?
Surprisingly, yes. New neurons created in adulthood are short-lived and don’t always translate to improved brain function in every aspect. In addition, an extended period of decline in the rate of neurogenesis sometimes follows an acute increase in adult neurogenesis, possibly contributing to a chronic clinical condition. (19)
New neurons don’t behave the same way that those created in childhood do. They are highly excitable but they don’t move around as much or penetrate through all layers of the hippocampus. (20)
Implications of Neurogenesis
Research continues into the practical function of adult neurogenesis and how its stimulation can be put to therapeutic use for injury and disease. Do whatever you might in this regard, increasing neurogenesis won’t make you smarter or preclude some memory loss as you age. It is important in the sense that if you keep your brain challenged and working, exercise the rest of your body regularly, and eat a healthy diet, science suggests you can maintain neuroplasticity so you can keep your marbles.