Pumping the neurons
Some simple advice for all those baby boomers who get queasy when they misplace their keys: Every bit as important as financial planning or choosing that retirement home is your daily brain plan to ward off Alzheimer's and adapt to the mental changes of normal aging.
It's normal as you age to have slower recall, but that's mostly a decline in the speed of information processing. The neural networks of the brain are preserved, which means knowledge is preserved, as are executive brain functions, which enable one to plan a day, pay bills, or embark on new adventures. You may forget where you placed your keys for a while--but you don't forget that you need keys or forget how to get home. Indeed, there is a vast difference between slowing down and getting your wires cut, as occurs in Alzheimer's.
The specter of Alzheimer's is unmistakable if only by its relentless deterioration: the memories gone, the vacant stare, the flat personality, the mind that cannot reason, the hobbies untended, the confusion, even hallucination. In the end, it's the loss of self in the depths of dementia.
The first region of the brain to be attacked in Alzheimer's is the memory-processing area called the hippocampus, deep in the brain. Blood flow decreases and nerve cells deteriorate and die as a dense protein called amyloid forms plaques that strangle nerve cells. Smaller amyloid clumps also choke off the elaborate electrical and chemical signaling that makes the central nervous system function. In time this process spreads almost like a cancer, eroding more and more brain function.
Psychology's tools. The holy grail of Alzheimer's researchers is to stop this degenerative process altogether by cleaning up amyloid debris and blocking further accumulation. But this biochemical solution is a while off. What we do have in our grasp today are ways to delay the impact of the creeping attack, perhaps by many years, using psychology to drive biochemistry. We know we can fortify the brain and even build new networks to bypass areas of injury.
A decade ago this idea would have been heretical. It was neuronal dogma that the brain was chiseled in stone with a fixed number of neurons that could only be lost, not gained, over time. That was before better imaging and molecular technologies gave us a closer look at the brain in motion. Though some of the brain is hard wired, it also has a "plastic" dimension, with new connections being lost or gained and neurons disappearing and new ones growing depending upon stimulation. And it now seems that this "plastic" power can be harnessed to fend off Alzheimer's.
Those with better IQs and more education--who are also more likely to engage in brain-driven activities--have less risk of developing dementia. It's presumed that they have more brain reserves that can take over when nerves are damaged. Indeed, studies have shown that with the same amount of brain degeneration, this group shows far fewer symptoms. This notion of "use it or lose it" was confirmed by findings from the Bronx Aging Study reported in last week's New England Journal of Medicine.
Purely physical activities like pumping iron or doing housework may have health benefits, but they don't lower the risk of Alzheimer's. By contrast, reading, crossword puzzles, playing board games like chess or checkers, playing musical instruments--and even dancing--do. And the more the better. Frequent dancing, for example, which demands musical concentration and knowing where to put your feet while engaging in polite conversation, showed a robust 75 percent reduction in risk. Activities like knitting, gardening, and traveling afford similar benefits. Furthermore, cognitive activities cut risk regardless of baseline IQ or education level, suggesting that favorable brain remodeling may be caused by more-recent brain-stimulating tasks rather than some fixed wiring of the past. Proving causality, of course, is tricky.
In addition to mental exercise, other psychological factors figure into normal aging and dementia. Chronic stress, depression, and social isolation all wreak havoc with memory and add to cognitive deterioration. Chronic elevations of the hormone cortisol--which comes with both stress and depression--cause the memory center of the brain to shrink and in some cases to lose neurons in the brain's memory circuits. Indeed, this is why most aging specialists encourage patients to read more, stress out less, and have good social outlets.
So here's a prescription: a few chapters of Harry Potter, the New York Times Sunday crossword puzzle, and some ballroom dancing to relaxing music with a partner you really like. That just may be the real secret to happy retirement.
This story appears in the June 30, 2003 print edition of U.S. News & World Report.