July 20, 2011

More Exercise, Better Memory

Looks like it's Exercise Week on the blog. After posts on the subject these past two days, I was going to change the subject. Then my mailman delivered the summer 2011 issue of The Johns Hopkins Memory Disorders Bulletin. I saw that it included an article: "Boosting Memory with Exercise."

Here's a summary:

Four different medications are used to treat Alzheimer's, but none of them slows, stops, or reverses the cell death underlying the disease. Experts are looking for innovative ways to put the brakes on this horrible disease. Leading authorities believe if Alzheimer's Disease (AD) onset can be delayed just 12 months, over nine million fewer cases would occur worldwide. Here's why: since AD primarily afflicts the aged, any delay increases the chances the patient will die of something else.

Regular exercise may offer the relief that other treatments have failed to deliver. In recent years, many studies have examined this exercise-dementia link, and most of them have been hopeful. Still, no study has provided proof positive that exercise can prevent or slow dementia.

Researchers have offered many theories to explain why exercise might delay dementia: benefits from weight loss, improvements in insulin resistance to shield brain cells, a bolstered immune system.

Exercise as "Miracle-Gro" for the Brain
It's clear that exercise increases the levels of brain-derived neurotrophic factor (BDNF), dubbed "Miracle-Gro for the  brain." Experiments with mice indicate that BDNF may actually help reduce the risk of AD.

Many studies with humans confirm: physical activity can protect the brain. A University of Virginia study (involving 2,257 men aged 71 to 93) found that those who walked less than 400 meters a day were almost twice as likely to develop Alzheimer's as those who walked more than 2 miles every day. ("Hooray!" says this walker.)

In a similar study involving women 70 and older, the more physically active participants outscored their less active counterparts on cognitive performance tests, and showed less cognitive decline generally. The researchers concluded: "The apparent cognitive benefits of greater physical activity were similar in extent to being about three years younger in age and were associated with a 20 percent lower risk of cognitive impairment."

Exercise and the Brain's Hippocampus
The hippocampus is smaller that the tip of your pinky. But it plays a significant role in memory and spatial reasoning. While the hippocampus normally shrinks as people age -- and shrinks more rapidly in those with AD -- scientists now agree that it can grow throughout life, but only if people remain physically active.

A recent study found that moderate exercise for a year resulted (on average) in a two percent increase in the size of the brain.

The Johns Hopkins bulletin concludes this way:
"Some believe that not exercising regularly has the same negative health impact as smoking a pack of cigarettes each day. Now it's up to you to do something about it. Lace up your exercise shoes and head outside."
Why on earth would we choose to ignore that advice?

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