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by P. Murali Doraiswamy, M.D., AARP The Magazine, March/April 2010 issue
Gary Small, M.D., remembers the patient well. An accomplished mathematician in his early 70s, the man consulted Small after struggling with calculations, and after his wife noticed he was getting cranky. Small, director of the UCLA Center on Aging, put the mathematician through a battery of tests—and the man got top scores on all of them, including 30 out of 30 on a memory test and a whopping 140 on his IQ test. So when Small saw the patient's brain scan, he was stunned: it had all the markings of full-blown Alzheimer's disease.
"Usually, people with such profound brain changes can barely carry on a conversation," says Small. "This man was still doing high-level mathematics." Though the case is extreme, it is not unique. In fact, up to 20 percent of people autopsied who had no major memory problems are discovered to have had Alzheimer's, says Yaakov Stern, Ph.D., a neuropsychologist at Columbia University College of Physicians and Surgeons in New York City.
How does the brain continue to function—sometimes quite efficiently—despite changes that should cause severe disability? An answer, many scientists believe, is "cognitive reserve": the combination of a person's innate abilities and the additional brainpower that comes from challenging the mind. Studies show that diverse, mentally stimulating tasks result in more brain cells, more robust connections among those cells, and a greater ability to bypass age- or disease-related trouble spots in the brain. The more you work your mind, the greater your cognitive reserve. And the greater your reserve, the greater your ability to withstand the inevitable challenges of aging.
As a doctor specializing in memory problems, I have seen recent discoveries offer new hope and guidance to people who want to maintain peak brain performance. Although we don't know how to stop the devastation of dementia, we learn more each year about combating the small losses in brainpower that often come after 50—even while you enjoy the brain benefits of getting older (and yes, as you'll see below, those benefits do exist).
Despite what our youth-oriented culture tells us, mental decline after 50 is not a given. In fact, in some ways the healthy brain gets stronger with age. Studies confirm that accumulated knowledge and expert skills (a.k.a. wisdom) increase as you get older. In addition, emotional savvy, such as not dwelling on negative thoughts, also appears to grow with age, as demonstrated in a recent Duke University study. Researchers showed a set of photos to study participants. Some of the photos were of neutral items such as household objects; others were distressing shots of violent scenes. Tested later, participants in their 70s remembered about the same number of neutral images as did those in their 20s, but the older people remembered fewer of the unpleasant ones. Cell-signaling activity in the older group suggested their brains filtered out bad memories.
Other brain functions may not improve with age, but they don't automatically wane either. One example is higher-order decision making such as choosing the best investments. Older people do as well as younger ones on tests that measure this function—as long as they aren't rushed.
And that's the catch. Some brain functions tend to decline with age, and speed is one of them. The likely reasons are loss of neural connections, blockages of blood supply, and decreases in nerve-signaling chemicals.
Memory can also diminish with age, though only certain types. Learned skills such as driving are wired so firmly that they typically do not decline unless you have a disease such as Alzheimer's. Memory for events (called explicit memory) is a bit more vulnerable, although episodes that really made an impression, such as meeting your spouse, are generally secure.
If your memory is suffering, it's most likely your short-term memory. This ability—which includes "working memory," where events are held before being filed for the long term—usually peaks by the early 30s. That's why memorizing complex new information, such as a foreign language, can get harder as you get older.
So how do you keep your brain at its best? By growing new brain cells, for starters. Long thought impossible, this turns out to be relatively routine in lab animals and, thus, maybe in humans. Scientists suspect that certain lifestyle habits can spark the cells' growth.
In 1998, Fred Gage, Ph.D., and his colleagues at the Salk Institute for Biological Studies in La Jolla, California, showed that the memory centers of adult human brains can grow new cells. Since then, studies by Gage and others have suggested that the more physical and mental exercise you get, the more brain cells you grow, the longer they survive, and the better they connect with other nerve cells. Exercise, such as brisk walking for 40 minutes four times a week, increases bloodflow to the regions of the brain shown able to grow new cells. "In our lab, when we discovered this, people started taking walks during their lunch hour," says Gage. Movement is so crucial to brain health that some of the cognitive changes blamed on aging may in fact be the result of inactivity, he adds.
Another simple, brainpower-boosting habit: pay attention to what you're doing. As we age, we become more prone to distraction, thanks to some of the same brain changes that can hamper our thinking speed. But even a split-second loss of focus can prevent a memory from being properly stored. So when you put down your glasses, focus on where you put them; they may be a whole lot easier to find.
Many memory problems stem from treatable conditions such as vitamin B deficiencies, depression, thyroid problems, or uncontrolled vascular disease. So if you notice changes, a visit to the doctor could set you straight.
If you're worried about your response time, practice can help quite a bit, researchers have found. After a group of people 65 and up did exercises in which they searched for and matched images, 87 percent of them improved their speed, according to a multicenter study led by the University of Alabama. And older adults who regularly tutored elementary-school students saw improvements in their own cognitive function after six months, a 2009 Johns Hopkins study showed.
Several of the activities that help you stay sharp are also good for your heart, your immune system, and your body's other machinery. In fact, a recently published study of 2,500 people ages 70 to 79 found that 30 percent of the group saw no decline in their mental performance or improved on cognitive tests over the course of eight years. And that fortunate 30 percent were more likely than the others to have some or all of these healthy traits:
Note that most of the time, these behaviors are under our own control.
Everyone can maximize his or her brain health. Living an active life—resisting the siren call of the couch and the remote control—is your best bet for staying sharp. And here are ten more brain-boosting activities:
Most important, shun gimmicks. No product can build extra brainpower instantly or effortlessly. But with challenging new habits, you can make your mind steadily sharper and stronger—now and for the rest of your life.
P. Murali Doraiswamy, M.D., is chief of biological psychiatry at Duke University Medical Center and coauthor of The Alzheimer's Action Plan. A writer on that book, Maryland freelancer Tina Adler, contributed to this article.
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