Media Relations

Author: Elizabeth Landau - CNN.com Health Writer/Producer Date: Thursday, November 8th, 2012

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One of the sad realities about Alzheimer's disease is that there's no way of preventing it – at least not yet.  We know some people are genetically or biologically at greater risk than others, but researchers want to find out how we can fight it off, or at least delay it.

The strongest evidence for a lifestyle choice associated with Alzheimer's prevention is exercise.  A new study in the journal Neurology supports that, and also suggests that working out is more effective at protecting the brain than cognitive challenges such as games and puzzles.

Researchers studied a group of nearly 700 participants from Scotland, all born in 1936, who reported their leisure and physical activity levels at age 70.  They rated physical activity on a scale from "moving only in connection with necessary (household) chores" to "keep-fit/heavy exercise or competitive sport several times per week," the study said.  Participants also rated how often they engaged in various social and intellectual activities.

Then, at age 73, the scientists used magnetic resonance imaging (MRI) to measure certain biomarkers in the brain among these participants.

It appears that people who participated in more physical activity generally showed less brain shrinkage and fewer white matter lesions, both of which can be signs of Alzheimer's disease.

Gray matter mostly consists of nerve cells, neurons, and primarily is linked with processing and cognition, according to the Alzheimer's Association.  White matter, on the other hand, is mainly composed of nerve fibers, and coordinates communication between various brain regions.

Researchers found that intellectual and social engagement weren't as helpful to the brain, although there have been hints that these also carry benefits.

The results of this study are not surprising to Heather Snyder, senior associate director for medical and scientific relations at the Alzheimer's Association, who was not involved in the study.  Physical activity helps to promote a healthy heart, and the well-being of the heart and brain are interrelated.  An unhealthy heart isn't as efficient at pumping blood, which the brain needs.

"In terms of the exact mechanism, there's a lot that we don't know," she said.

Cognitive exercises don’t hurt, but the strongest evidence from research conducted so far suggests exercise helps prevent Alzheimer's later in life, Snyder said.

As to how much exercise is optimal, what kind, or whether it's too late to start amping up physical activity after a certain age, researchers aren't sure, Snyder said.

Hints are emerging, however.  Research presented at the Alzheimer's Association's International Conference in July suggests that strength training could be the best exercise intervention.

Among the small studies presented, one demonstrated that women between ages 70 and 80 benefited from weight-lifting, walking and balance exercises, but those who used weights showed the most improvement.  Scientists found that people who began with the highest cognitive baseline responded the best in this study.

What's needed is a long-term, large-scale study to track a lot of people over time, so that researchers can more definitively examine the benefits of different kinds of exercise, and how much and how often different activities should be done to gain the most Alzheimer's protection, Snyder said.

Source: http://thechart.blogs.cnn.com/2012/10/23/exercise-may-preserve-brain-better-than-games/?hpt=he_bn2