Once upon a time, medical experts believed that the adult brain couldn't make new brain cells, or more specifically, new nerve cells, aka neurons. The process of manufacturing new nerve cells, known as neurogenesis, seemed limited to the young.
Fortunately, we now know this is not the case. Although it's true that neurogenesis surges during our early years of life and declines significantly as we age, new neurons do continue to be born. In fact, the adult brain makes hundreds of new nerve cells every day, and they are being produced in an area of the brain that is intimately involved with memory, mood, learning, and emotion-the hippocampus. Therefore, it appears that we have a chance to help our memory as we get older-good news indeed!
According to Jonas Frisen from the Karolinska Institutet in Sweden, the adult brain produces an estimated 700 new neurons daily in the hippocampus. Given that the human brain consists of billions of neurons, 700 new nerve cells doesn't seem like much. However, as Sandrine Thuret, PhD, of Kings College London and principal investigator and lecturer in neural stem cell research revealed during a TED talk, "by the time we turn 50, we will have all exchanged the neurons we were born with in that structure [hippocampus] with adult-born neurons."
Since the adult brain has this ability to make new brain cells, two critical questions immediately come to mind:
- Which of our activities or behaviors can disrupt neurogenesis?
- How can we promote neurogenesis and thus help memory, learning, mood, and emotional health?
The answers to these two questions mostly involve lifestyle choices but include health issues as well. For example, Thuret explained how research has shown that depression is associated with lower production of neurons. However, treating depression with antidepressants can increase new nerve cell production while contributing to a decline in depressive symptoms.
Similarly, cancer patients treated for their disease often report depression even after the cancer is cured, and that's because the cancer treatment, including radiation, can have a significant negative effect on neurogenesis. Over time, however, new nerve cell production can begin again.
On a more practical level, Thuret offers some everyday lifestyle factors you can change or adopt that can facilitate the production of new brain cells and help with your memory.
- Get sufficient sleep. Regularly sleeping 7 to 8 hours supports new brain cell production while too little dampens neurogenesis
- Manage stress. Unmanaged stress disrupts new nerve cell production. Whether it's deep breathing, meditation, yoga, tai chi, progressive relaxation, or another healthy stress reducer, practice it regularly!
- Keep learning. Continue to exercise your brain by learning new things, whether it's via hobbies, taking classes, learning a new language, playing a musical instrument, etc. It all stimulates neuron production.
- Engage in sex. Sexual activity is a new brain cell booster. Use your imagination!
- Enjoy aerobic exercise. Thuret used running as an example of exercise that's been shown to promote neurogenesis, but any aerobic exercise will likely be beneficial.
- Restrict calorie intake. It's been shown that reducing caloric intake by 20 to 30 percent boosts new nerve cell production. A 2013 review of the impact of calorie restriction on neurogenesis noted that "Calorie restriction is the only non-genetic intervention that reliably increases life span and healthspan across multiple organisms." It's important to avoid malnutrition when reducing calories, however.
- Try intermittent fasting. There are several approaches to intermittent fasting and a number of studies that have looked at various approaches. One method is to fast every other day, which is likely too severe for many people. Another is to fast one day per week or every 10 days; yet another is to eat a normal amount of calories on some days and then on fasting days, reduce caloric intake significantly to about 500 to 600 calories. Intermittent fasting can go hand-in-hand with calorie restriction, although experts tend to believe the fasting approach is better for neurogenesis.
- Focus on "brainy" foods. Eating foods high in flavonoids (e.g., blueberries, dark chocolate) and omega-3 fatty acids (e.g., fatty fish such as salmon, tuna) promote neurogenesis, while a diet rich in saturated fat and/or that includes alcohol will decrease new brain cell production. One exception in the latter category is red wine, which contains resveratrol and may be considered a "neurogenesis-neutral" drink by Thuret. Practice moderation, of course!
- Choose to chew. Japanese research has suggested foods that require chewing, such as crunchy foods, support neurogenesis while following a soft diet can interfere with it.
It's entirely possible to continue producing new brain cells as we get older. If you make some lifestyle modifications, you can effectively battle aging and memory loss and improve your quality of life.
Sources Arslan-Ergul A et al. Aging, neurogenesis, and caloric restriction in different model organisms. Aging and Disease 2012 Aug; 4(4): 221-32
Chen H et al. Chewing maintains hippocampus-dependent cognitive function. International Journal of Medical Sciences 2015; 12(6): 502-9
Dana Foundation. The brain's metabolic mysteries
Sandrine Thuret. You can grow new brain cells. Here's how. TED Talk.