Highway Brain and the Earthquake Dementia

Our brain changes as we grow older. Changes dictated by the slow shrinking of the brain, creating a widening of the pockets inside the brain. And there are also changes in parts of the brain used for certain tasks.

We are learning more about these changes because of a new technique of seeing into the brain called functional Magnetic Resonance Imaging. The functional part is that we can have people perform an activity while we watch their brain’s activity.

On the whole we witness variable results when we compare older and younger adults. Sometimes there is less activation among older adults, sometimes more activation, and invariable older and younger adults differ in which parts of the brain they use while undergoing the same activity (eg reading.)

The brain is a wonderfully clever but lazy organ. It works as hard as it has to and nothing more. Which is why sometimes it is hard to learn, because we have to persuade it that it has to. Like any precocious teenager, they will do enough to get by. The brain is like that teen.

David Snowdon studies 678 nuns—Catholic members of the School Sisters of Notre Dame—who are 75 to 106 years of age. The nuns undergo extensive testing and when they die, his team examines their brain. It was Snowdon who first reported a very strange anomaly. He found that a third of the nuns who for all intents and purposes acted normally throughout their life, when they performed the autopsy, they found that their brain had the disease of Alzheimer’s. This finding has since been found in other populations, notably in Sweden where otherwise healthy and competent older adults were found to have diseased brains.

The quick answer to this finding is that some people have “cognitive reserve”. Basically they have more brains and so they can afford to loose some to the disease.  But this does not explain why certain occupations—academic, research, engineering and art, occupations that develop your brain—do not protect you from dementia. It seems that the reserve is not just in size but that the reserve need to be in quality—how you develop and grow your brain.

Like a precocious teen, the brain knows of ways of escaping from its many duties. Doing things that we take for granted—like reading for example—the brain develops an interstate of neural pathways that makes it easy for it to accomplish that repetitive task.  What seems to work is when we trick our brain in developing new pathways.

In a 21-year study of older adults, 75 years and older, Robert Katzman and Joe Verghese, found that mental activities like reading books, writing for pleasure, doing crossword puzzles, playing cards as well as playing golf, swimming, bicycling, dancing, walking for exercise and doing housework did not offer any protection against dementia with some important exceptions:  frequent dancing, playing an instrument and playing board games.

Creating new pathways is what works. When disease interferes with the flow of traffic, then having alternate pathways helps divert traffic. This is what seems to be happening and why it is not just the size of the brain but the networks that we develop that protect us from dementia.

Mario Garrett, Ph.D., is a professor of gerontology at San Diego State University and can be reached at mariusgarrett@yahoo.com