Growing new brain cells is lifelong, but the process slows down as we age. Exercise helps to speed this process back up and get the brain cells working again.
Guest Posting It wasn't that long ago that scientists believed that adults couldn't grow new neurons in their brains. However, work over the past few years has debunked this myth. We now know that adults continue to grow new neurons throughout life, a process called neurogenesis. Yes, new growth slows after middle age, but it continues. But there are things you can do to keep the birth rate of new brain cells higher, which we'll get to in a minute.
Continuing to grow new brain cells can help in several ways. First, the cells are mostly born in an area called the hippocampus, which is crucial for learning and memory. Maintaining neurogenesis helps maintain memory function. Second, maintaining these new neurons seems to help with depression. The hippocampus is also critical for stress regulation, and neurogenesis is an essential part of how antidepressants work. Thus, the birth of new brain cells is important for cognitive and emotional functions. In the past, we referred to these as your IQ and your EQ.
Exercise has been known for some time to increase the rate of neurogenesis. Many studies show that laboratory animals that are allowed to exercise increase the number of new neurons born in their hippocampus compared to animals that are not allowed to exercise.
Although these studies in humans are difficult (for technical reasons), several studies suggest that the same thing happens. In human trials comparing exercise groups to control groups, exercisers consistently show improved cognitive abilities and increased function of specific brain regions, including the hippocampus.
A new study by Wu et al. published in the September 18, 2008, issue of the Journal of Applied Physiology also shows that exercise can increase the connectivity of new neurons. It is not enough to create new neurons. You also need to connect them to other neurons so that they are fully integrated into the brain's circuitry so that they can do their thing.
On average, each neuron in your brain makes about 10,000 connections. It's not good for a neuron to just sit there and talk to itself. To have real value, it must become part of the network. When you learn things, you actually increase the connectivity between neurons, and that's the most important thing.
In fact, the number of connections in your brain is probably far more important than the number of brain cells when it comes to maintaining cognitive function. Wu's new study shows that exercise increases both. It increases the number of newly formed neurons and the amount of branching that each new neuron makes.
Neurons are shaped like trees. The more branches they have, the more connections they can make. In Wu's study, exercise increased the number and length of branches on new neurons.
Finally, the most important part of the new study looked at how exercise affects the rate at which new brain cells grow and the amount of branching as we age. Basically, the researchers confirmed that the rate of neurogenesis declines with age, and that exercise in early middle age has a major effect on increasing the rate at which new brain cells are born. Exercise in older age also increases neurogenesis, albeit to a lesser extent.
Here's the interesting part, though. In their experiments, sedentary rats had approximately the same length of neuronal branches in middle age and in old age. But the exercise rats had much longer branches. In fact, old exercisers had longer neuronal branches than younger sedentary rats. This is great news because many studies show that branch length and connectivity may be a better indicator of cognitive health than the number of newly born neurons.
We know that lifelong learning is one way to encourage greater neuronal branching and connectivity. Now, this new study shows that exercise can do that for older adult brains, too.
Bottom line: physical exercise is a great way to keep your brain in shape.
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