Prime Time - Jane Fonda [53]
The good news is that clear evidence from functional imaging shows that the brain has great reserves of plasticity. It is capable of adaptation and reorganization, acquiring new skills, absorbing new data, and changing its circuitry in response to the cognitive demands placed on it. Moreover, where there has been a lessening of certain cognitive functions, such as inductive reasoning, spatial orientation, and short-term memory, these functions can be restored with training.
As we age, our brain volume declines, but some parts are more susceptible to loss of volume than others. I learned from the late Dr. Robert Butler, at the International Longevity Center, that there are many pathways for processing thought. “The circuitry in your brain is interconnected in multiple ways,” he told me, “resulting in what neurologists call ‘neural redundancy.’ Think backup systems: When one goes down, another is at hand to help carry the load.” As certain neural networks are broken, the brain searches for new networks. If cognitive functions that have been handled by certain regions of, say, the left frontal lobe are impaired, the right frontal lobe may be recruited to help its neighbor. In stroke victims, for instance, other parts of the brain take over the recovered functions from the parts that are damaged. This is known as “compensatory recruitment.” And it’s good news, because it provides evidence for the elasticity and adaptation of the brain.
While younger people use one side of their brain for a given functional task—the right frontal cortex, for example—older folks will often use both sides to perform the same task. Their cognitive processes may be slower, but that doesn’t mean they have functional impairment. Are you one of those people who panics every time you call your son by your brother’s name, or your grandson by your son’s name, or when you can’t think of something you should know well—like your stepson’s name—and see it as a sign that you’re about to get Alzheimer’s? Don’t worry, things like forgetting names are not predictive of Alzheimer’s. When I forget a name or a fact, rather than furrow my brow and try to force myself to remember, I let it go—and often as not, it comes to me later. When I think I’ve lost something, rather than panic, I go about my business, and sure enough, it’ll turn up in the purse I carried yesterday, or in the backseat of my car, where I put it two days ago. I’ve learned to relax into memory, if you will.
Brain-imaging technology shows “that not only is normal brain shrinkage less than we feared, but much of what is lost may be judicious ‘pruning,’ ” says Dr. George Vaillant, director of the Harvard Study of Adult Development. He likens this to an attic that has filled up carelessly over the decades but now, with age, we clean it out and select only the most cherished, meaningful items to keep. Dr. Denise Park, director of the Center for Vital Longevity at the University of Texas at Dallas, puts it this way: “You may lose a bit of horsepower, but you are highly efficient as you rely on your knowledge and experience instead. Maybe this is the Prius model of cognitive aging.”1
Exercise and the Brain
Science shows us that seniors who have remained fit and who continue to exercise continue to have good brain functioning. Cardiovascular fitness is perhaps one of the best things we can do to maintain our brain health. Even when older people who have never been particularly active engage in moderate exercise, they see their cognitive functioning improve. This is because physical exercise causes an increase in a chemical nerve growth factor that allows brain cells to grow, stimulates the connections between them, and helps in memory function.
Because of the increased obesity and inactivity in the United States these days, it is possible that we will lose, as a country, all the health gains of the last fifty years. Some economists suggest that we could lose it in a single generation. This is frightening