Imagine if there were a drug that could reduce the risk of dementia by 60%. It would be the most talked-about drug in history, but this astonishing finding has been fairly quietly received. EXERCISE IS THE DRUG!

It seems that a more accurate rule for our brains is “Use it or lose it.”

In the late 1970s, research by Mark Rosenzweig of the University of California at Berkeley and Michael Merzenich of the University of California at San Francisco and others began to show that the brain’s circuitry changes microscopically with experience and activity. Dr. Rosenzweig and colleagues found that, with environmental stimulation, the brains of animals grew in key areas. Dr. Merzenich discovered that if an animal stopped using a body part, the brain area that processed sensory input from that part weakened or was taken over to perform another function. These findings have since been replicated many times.

The mainstream view in neuroscience and medicine today is that the living brain is actually “neuroplastic”—meaning that its “circuits” are constantly changing in response to what we actually do out in the world. As we think, perceive, form memories or learn new skills, the connections between brain cells also change and strengthen.

This capacity is the foundation for the brain’s distinctive way of healing. If an area is damaged, new neurons can often take over old tasks. Nor are we just our neurons. Our memories and experiences are also encoded in the patterns of electrical energy produced by our brain cells, like a musical score. As with an orchestra, when one member of the string section is sick, the show can still go on if a replacement has access to the musical score.

This new “plastic” understanding has major practical implications for how we treat brain problems and maintain brain health. And it has led to some surprising discoveries.

Consider dementia, which in some form affects some 15% of people in the U.S. over age 70 and advances rapidly as we age. A brain with Alzheimer’s, the most common form of dementia, turns out, by various measures, to be a brain that is losing its overall plasticity. It shrinks and loses connections. But a growing body of research has found that exercise, both mental and physical, can lower the risk of experiencing dementia.

But the activity with the biggest impact on risk was walking at least 2 miles a day, biking 10 miles a day or engaging in some other regular, vigorous physical exercise. All five of these factors have been found in other studies to promote the general health of two types of cells in the brain: neurons and glial cells (which interact with and protect neurons).

One reason is that many people assume that Alzheimer’s disease is “all in your genes.” But as neurologist and dementia researcher Tiffany Chow of the Rotman Research Institute and the University of Toronto points out, environmental factors “interact with…genetic makeup to eventually allow or deny dementia a foothold.” Even having multiple copies of the genetic materials associated with risk, Dr. Chow points out, “is not sufficient to produce Alzheimer’s disease.” For the majority of people, how they live matters. 

The research in Wales followed at least 10 other studies showing that exercise in midlife was associated or correlated with lower rates of dementia—and that a lack of regular exercise corresponded with higher rates of dementia.

Read the full article: http://www.wsj.com/articles/SB20167761076414843692504580443981315539578