FORTUNE -- Not so long ago, conventional wisdom among neuroscientists held that the human brain was doomed to deteriorate with the passage of time, and there wasn't much anyone could do about it.
Instead, a raft of recent studies, aided by brain-imaging technology, all point to a much different conclusion: Our grey matter can keep on regenerating throughout life, producing new active cells all the time. "Your brain is a living and constantly developing dense forest with billions of neurons and synapses," says Alvaro Fernandez, founder and CEO of market research firm SharpBrains.
The emerging science of neuroplasticity, which studies how our brains change and adapt, is revealing that, as with muscles, it's a case of "use it or lose it," he adds. "Once new neurons appear in your brain, where they stay and how long they survive depends on how you use them."
Fernandez is co-author of a book called The SharpBrains Guide to Brain Fitness that boils down the current explosion of new research in this area to specific advice on what to do now to guard against Alzheimer's and other forms of cognitive impairment later on.
By a lucky coincidence, there's plenty of overlap between what's good for your brain and what could turbo-charge your career. Consider these five tips:
1. Never stop learning. The latest research shows conclusively that, the better educated a person is, the less likely she is to suffer from age-related decline. "Highly educated people are likely to have mentally stimulating jobs," Fernandez notes, and that fosters the birth of new neurons. If you get into the habit of learning new skills throughout your career -- which also happens to make you more marketable and promotable -- your brain will thank you later.
2. Immerse yourself in another culture. In particular, learn another language. As U.S. business (especially marketing) becomes ever more bilingual, Spanish would be smart -- but, for the ultimate brain workout, pick Russian, Mandarin, or Arabic, whose different alphabets make them that much more challenging.
If you can, volunteer for overseas gigs, too. Not only do these make your resume stand out from the crowd, but "exploring and adjusting to new locations forces you to pay more attention to your environment" than staying home, Fernandez notes. Navigating an unfamiliar culture, even for a short time, is like calisthenics for your brain.
3. Seek out tough "stretch" assignments. "The goal is to be exposed to novelty and increasing levels of challenge, so the task never becomes too easy or routine," Fernandez writes, adding that this means "expending effort and getting out of your comfort zone." Variety is as important as challenge, several new studies show: "Excessive specialization is not the best strategy for maintaining long-term brain health. A bond trader may thus want to try an artistic activity, to stimulate brain cells that he or she rarely uses otherwise."
4. Manage stress. "Excessive stress, no matter whether induced by external events or by your own thoughts, actually kills neurons and prevents the formation of new ones," Fernandez notes. Obviously, you don't want that. The SharpBrains Guide to Brain Fitness goes into detail on how physical exercise, meditation, and even having a good laugh help to protect your brain from the ravages of too much pressure, while heading off job burnout too. Taking a real vacation once in a while is also a proven stress fighter.
5. Have lots of friends. Not only is a vast and varied network of pals a huge advantage when you want to change jobs (or hire the right person), but it turns out that "social engagement contributes to brain health," Fernandez writes. New research shows that regularly interacting with a wide range of other people contributes to "both short-term performance boosts and the buildup of cognitive reserve."
Is there an ideal number of friends? The human cerebral cortex, it seems, can efficiently process only a limited number of relationships, and that number (known to neuroscientists as Dunbar's number, after the researcher who found it) is 150. In an interesting aside, Fernandez notes that, although some people have thousands of Facebook friends, "the typical number is around 120, which corresponds roughly to Dunbar's number -- that is, the number of friends and acquaintances people generally have in real life."
Thanks partly to Gen Y up-and-comers who want international experience but on their own terms, one size no longer fits all.
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