Seven ways to stimulate neurogenesis
Exercise is one of the best ways to increase neurogenesis, largely because it boosts production of brain-derived neurotrophic factor (BDNF). BDNF is a protein that acts like Miracle-Gro for brain cells: it stimulates the growth of neuroblasts, helps them survive, and encourages the formation of new synapses. The positive effects of exercise are enhanced by environmental enrichment (EE), which can include being in new, stimulating surroundings or going outdoors.
Sustained aerobic exercise like running increases neurogenesis, while resistance exercise has not been shown to have the same effect. Dr. John Ratey, the author of Spark: The Revolutionary New Science of Exercise and the Brain, recommends doing both aerobic exercise and activities that demand focus and coordination, like martial arts, dance, rock climbing, and yoga, in order to fully stimulate your brain.
Learning improves the chances that neuroblasts will survive, mature, and integrate into neural circuitry. This is why continuing to stimulate your brain by learning new things throughout life is so important. For best results, scientists recommend exercising first in order to increase the production of new neurons, then spending time learning your new skill to help the new neurons survive and integrate. And be sure to let your learning be fun; when learning becomes stressful, it can decrease neurogenesis.
In rat experiments, sex increases the number of new neurons in the hippocampus. But regular sexual activity is best; a single sexual encounter also increases levels of the stress hormone corticosterone. Daily sexual encounters for 14 consecutive days do not raise corticosterone levels, and actually decrease anxiety behavior while still promoting neurogenesis. It’s also interesting to note that female rats only experience an increase in neuronal survival when they’re in control of the sexual encounter. Researchers speculate that when they’re not in control, female rats experience stress which prevents their new neurons from surviving. Neither of these experiments have been replicated in humans, but it’s easy to see how the same principles apply to short-term versus long-term relationships and male-female dynamics.
Living in groups helps us survive, so it’s not surprising that socializing promotes production of new brain cells. Neurogenesis is higher in socialized rats compared to rats kept in isolation. Isolated rats show a significant reduction in BDNF in the hippocampus, and they also perform worse on memory tasks. Social isolation also increases stress, and even cancels out the positive effects of running on neurogenesis. So if you live alone, be sure to make socializing part of your regular routine.
There is a long list of foods that promote neurogenesis. You may have heard that blueberries are brain food, and it turns out that strawberries are too (it’s the polyphenols). Grapeseed extract, turmeric, green tea, and resveratrol (found in peanuts, tree nuts, grapes, cocoa, wine, and berry fruits) also promote the growth of new neurons. And fatty fish, seaweed, algae, walnuts, and flax, chia, and hemp seeds contain omega-3 polyunsaturated fatty acids (PUFAs), which have been shown to promote hippocampal neurogenesis and improve spatial memory.
The idea of fasting is not a popular one—most people don’t like being hungry. But the practice of intermittent fasting is a new trend due to research showing its benefits for a wide range of health conditions. We evolved to survive during periods of fasting because food wasn’t always available. As a result, intermittent fasting is built into our physiology, and research shows that it benefits our health in many ways. Intermittent fasting lowers our insulin level and blood pressure, reduces inflammation, helps clear out toxins and damaged cells, improves our stress resistance, lengthens our lifespan, and reduces incidence of diabetes, obesity, and cancer. And of course, it increases neurogenesis and levels of BDNF, and prevents neuron death in the hippocampus.
The simplest form of intermittent fasting limits all food intake to a certain window of time, like 6 hours a day. Researchers recommend the circadian rhythm fasting approach, in which you start eating in the morning and finish consuming all your food by mid-afternoon or early evening. A 2018 study of men with prediabetes clearly showed the positive effects of early time-restricted feeding (eTRF): lower insulin levels, improved insulin sensitivity, and lower blood pressure and oxidative stress. Surprisingly, the eTRF group also had less desire to eat in the evening. Eating a big meal in the evening is probably not good for our health, and researchers suggest that the ways our circadian rhythms affect our body temperature, biochemical reactions, hormone levels, physical activity, and digestion of food may be why.
Finally, you can stimulate neurogenesis with meditation. The cerebral cortex of people who practice meditation is thicker in the areas associated with attention, interoception (internal sense of your body), and sensory processing. Differences in cortical thickness correlates with meditation experience, and meditation may offset age-related cortical thinning. Experienced meditators also have larger hippocampi than non-meditators, and yoga and meditation increase levels of BDNF.