Sunday, October 17, 2010

A walk in the park

It's no secret that exercising is key to maintaining a healthy brain as we get older. We hear it all the time. So why isn't everybody exercising? After all, it represents a form of personal health insurance, and it's way cheaper than Sun Life. The truth is, even though many people are aware that exercising is good for them, they are not compelled to change their lifestyle because it's not exactly clear what kind of exercise is best, how long you need to do it, and what exactly it does to help your brain. Well, I'm going to tell you.

In a recent study published in the journal Neurology, American researchers looked at 299 adults with a mean age of 78 years old. They evaluated how active each person was by measuring how many blocks they walked over the period of one week (this ranged between zero and 300!). The researchers then waited nine years (!), and then took brain images for all the participants and evaluated their level of cognitive impairment.

Not surprisingly, the more someone walked, the greater their brain volume after nine years. Greater amounts of physical activity predicted bigger volumes for several brain regions associated with thinking and memory, such as the hippocampus and the frontal cortex. What's more, the bigger brains associated with physical activity cut the risk for cognitive impairment in half.

The magic number in this study is 72. Walking a minimum of 72 blocks per week was necessary to see the bigger brain effect. Walking more than 72 blocks didn't lead to an even bigger brain. While I wouldn't necessarily shoot for walking only and exactly 72 blocks per week (as physical activity is also associated with a decreased risk for some illnesses), it's nice to have a baseline number, and to know that an exercise as simple as walking can make a difference.

So what are you waiting for?

Reference: Physical activity predicts gray matter volume in late adulthood: The Cardiovascular Health Study. Erickson KI et al. Neurology (2010) [Epub ahead of print].

4 Responses to “A walk in the park”

Anonymous said...

This post gives the pure and simple truth with the back-up of science. (Chuckling to myself.) How nice it is to be able to look inside people's heads to confirm what we probably already knew! Barbara

Thanks for your comment, Barbara! And you're so right, it's just confirming what we already know... But I guess some people need to hear something multiple times before they buy into it!

Mark said...

Thanks for the lecture at Science World the other day, Julie.

It occurred to me as I was out walking this morning (well over 72 blocks just today!) that the study you mention might not separate the physical aspects of walking from the mental aspects. After all, someone who walks 72 blocks a week is likely to have more time to think than someone who spends the time sitting in front of the television.

I recently heard it suggested that our unwavering focus on screens (televisions, computers, phones) might be leaving us with little time to think through what we experience and what we learn. Perhaps all that walking is maintaining brain plasticity by keeping our brains rather than our bodies active?

I suppose the way to decide would be to distinguish between people who walked 72 blocks listening to their iPods, and those who walked with their brains freer to think. I'm guessing that since this study dealt with 78-year-olds over 9 years ago, the subjects fell into the latter category!

Dr. Julie said...

Hi Mark,

Thanks for attending the lecture! And good for you for doing so much walking...

You may be onto something with your idea about the mental aspects of walking, and I love how you even thought about how to test it and what a good control group would be! Amazing!

Your idea may be supported by recent research into mindfulness (meditation), which has been shown to lead to great benefits for the brain. That said, researchers have been able to explain some of the benefits of walking through physical explanations as well. The answer is that walking probably optimizes brain function through both physical *and* mental mechanisms.

Thanks for the comment!

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