Contrary to what you might think -- and millions of Americans think it -- brain cells do not die off as people get older.
Instead, the branches of brain cells, known as dendrites, thin out, and their nerve systems become less effective. Imagine the brain as a tree that grows fewer leaves over the years.
But there's good news for anyone who frets about how much or little he might be remembering as life gets more packed with information, responsibilities and parking garages organized into areas marked 1G or 4C: Like a tree, almost any brain can be sustained with proper care and feeding.
In fact, boosting your memory and overall brain fitness can be refreshingly simple and attainable. It can be as easy as making better use of your five senses, plus an honorary sixth sense of emotion.
"The five senses provide a vast amount of information and understanding about the world," said Lawrence C. Katz, a neurobiology researcher at Duke University Medical Center in Durham, N.C. "Using them more fully taps into the full power of your brain and enhances its nerve connections."
Studies show emotional attachment strengthens memory recall, said James McGaw, a brain scientist at the University of California-Irvine. You remember things best that involve personal passions -- say, the first date with your spouse or a childhood visit to Wrigley Field. The brain makes the extra effort to store and stamp the input.
Our minds stay sharp by producing natural substances called neurotrophins. These brain nutrients feed the dendrites, which receive and trade information over connections called synapses. Parents with young children have likely heard about synapses, the focal point of early brain development in kids under 3. There has been plenty of research characterizing this time of life as the most fertile for nerve cell growth.
That might imply that the brain goes downhill from there. Not so. In fact, a 1998 study showed people in their 70s continue to grow new brain cells (neurons) in the hippocampus region of the brain, which is a vital center for learning and memory.
There are many ways to encourage your personal supply of neurotrophins and other brain goodies.
"One solution is to be more physically active," said Dr. Gastone Celesia, a physician and chairman of the neurology department at Loyola University Medical Center in Illinois.
Research shows physical activity increases blood flow to the brain, which is vital because oxygen comes in the bargain. The brain consumes more oxygen than any organ or tissue in the body. There is further evidence that moderate exercise, such as taking several brisk walks each week, can stimulate the dendrites and synapses.
You will remember more, concentrate better and experience mental clarity. All good reasons for finding time to work out.
Even such simple actions as taking a shower with your eyes closed, to amplify the use of other senses, can improve your sensory range and brain fitness, Katz said. Or you can brush your teeth with your non-dominant hand, sit in a different chair each meal time or visit a new park. He outlines 83 such exercises, which he calls "neurobics," as co-author of a new book, "Keep Your Brain Alive" (Workman, $12.95).
Technology can be counterproductive for the memory, Katz said. His prime example is the grocery store.
"Modern life has cut out all kinds of things our brains did during earlier generations and centuries," Katz said. "At the supermarket, you don't smell or touch your food much, you actually don't see it in many cases [of packaged foods]. I try to shop at the farmer's market whenever possible."
Look for role models
Some of our best role models might be grandparents or other elders who are both physically and mentally active.
"Think about the people you meet who have aged successfully," Katz said. "Their minds are lively. They tend to try new things. They make time for enjoying meals, maybe trying new tastes. They have active social lives."
Some studies have pointed to the mental benefits of playing bridge or doing crossword puzzles. Katz said playing cards qualifies as neurobic, while completing crosswords is mentally challenging but not a fully sensory experience.
Celesia's patients, as young as in their 40s, increasingly ask whether forgetting people's names is the first sign of dreaded Alzheimer's disease. The answer is, almost always, no.
Of course, there are times when memory loss requires medical attention. Any progressive memory loss is one warning sign. Not remembering a name is one thing; consistently misplacing your keys, then your car in parking lots, is more serious.
For his part, Katz said focusing only on your memory is like exercising only the biceps.
"You want a brain that can help you not just remember but one that helps you navigate through life," he said. "You want a brain that gives you flexibility to deal with the unexpected."
Food for thought
Here are some potential brain-boosters:
* Antioxidants: Getting more vitamins C and E, plus beta carotene, is a good overall health strategy aimed at neutralizing free radicals.
* B vitamins: Research shows people with higher blood levels of B-6 score better on memory tests, while higher amounts of B-12 and folate improve spatial skills. A daily supplement is recommended.
* Omega-3 fats: These "good fats" are found mostly in cold-water, oily fish and flax seeds (ground to break down the hull, then sprinkled into cereal, smoothies or salads). The key ingredient is docosahexaenoic acid or DHA, low levels of which have been associated with impaired brain function.
* Ginkgo biloba: A popular herbal product that has indicated increased blood flow to the brain in small studies. This is good news for older patients who might experience such loss of blood flow, but there is no evidence that ginkgo biloba will do much for the normal functioning brain.