Does exercise create neurons

The science of neurogenesis suggests it's possible to create neurons that improve your memory and thinking skills.


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There are many aspects of aging you cannot prevent, but surprisingly, memory trouble is not one of them.

"The dogma for the longest time was that adult brains couldn't generate any new brain cells. You just use what you were born with," says Dr. Amar Sahay, a neuroscientist with Harvard-affiliated Massachusetts General Hospital. "But the reality is that everyone has the capacity to develop new cells that can help enhance cognitive functions."

In this process, called neurogenesis, new neurons (brain cells) develop in the hippocampus, the brain region responsible for learning information, storing long-term memories, and regulating emotions.

Neurons in action

You naturally lose neurons as you age. Over time, this can affect different aspects of memory. "You may have trouble separating and storing new memories," says Dr. Sahay. For instance, you might mix up conversations you had with two people on the same day. You also may have difficulty recalling directions or other new information you've learned.

Even in old age, though, the brain still produces about 700 new neurons in the hippocampus per day, according to a 2013 study in the journal Cell. That many not seem like much, since the brain contains billions of neurons, but Dr. Sahay says this small amount has many valuable properties.

"And if you can increase that number even more through neurogenesis, you can help restore these key brain functions," he says.

Neurogenesis may even help protect against Alzheimer's, since the death of brain cells is linked to the disease (although many other factors also contribute to the disorder). And it may both treat and prevent depression. Depression slows neuron production, and research has shown that a series of depression episodes can shrink the hippocampus by 10%.

The scientific understanding of neurogenesis continues to evolve. Most research has focused on animals, but initial findings have identified certain actions that may be associated with stimulating neurogenesis in the human hippocampus.

Sustained aerobic exercise

Previous research has found that aerobic exercise generates more neurons than resistance training. Now, a study in the April 1, 2016, Journal of Physiology suggests that sustained, moderate-intensity aerobic exercise like jogging, power walking, swimming, or other similar activity might create an even greater response.

The study found that adult male rats that did sustained aerobic exercise for eight weeks had two to three times more hippocampal neurons compared with a control group that did no training. This type of exercise was also superior to resistance training and high-intensity interval training, which involves alternating between short bursts of intense exertion and slow-paced recovery periods. Even though this was an animal study, and more research is needed, the researchers suggest humans might gain the same benefit.

It is not clear why this type of exercise may work better. One theory is that sustained aerobic activity releases a protein in the brain called brain-derived neurotrophic factor, which has been shown to regulate neurogenesis.

Sex and other stress relief

A 2013 study found that both single and repeated sexual experiences enhance the number of newly generated neurons. However, frequency proved to be just as important as the act itself: any improvement in cognitive function was lost after a prolonged withdrawal period.

But the reaction is not necessarily about the physical aspect of sex, but rather what it can do: relieve stress. "Sex is pleasurable and a stress reliever, and research shows that chronic stress blocks neurogenesis," says Dr. Sahay. "So any activity you find rewarding and that lowers stress levels can have a similar effect."

Neurobics

Neurobics are brain exercises that emphasize unexpected stimuli. Studies have found these activities can improve memory. A study published Dec. 5, 2015, in The Journal of Neuroscience found that playing three-dimensional video games improved memory performance 12% more than playing two-dimensional games.

The reason, according to the researchers, is that three-dimensional games are more complex, as you need to learn and recall more information. "Any type of similar enriching experience that makes you focus your attention, even for brief periods, can have the same effect in the hippocampus," says Dr. Sahay.

For example, use your non-dominant hand to brush your teeth or stir your coffee. "It makes you concentrate more on the task," he says. "Even engaging in conversations and reading about new topics can help."

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