It is possible to grow new brain cells in adulthood, but the challenge lies in keeping these cells, which are produced mostly in the hippocampus when people learn new cognitive or practical skills. However, not all new knowledge acquisitions are equal: as people (or in the case of laboratory experiments on the topic, dogs and mice) get accustomed or conditioned to their newly acquired knowledge or skills (i.e., things become routinary) new cells that were produced in the course of their learning die out. But the flip-side is that some cells actually stay around if the learning or the mental exercise involved is, remains, or becomes more challenging. It’s basically a case of learning begets more learning; new brain cells are produced when one learns more, but for them to stick around longer or permanently, one must challenge one’s cognitive capacity or aptitude continuously. So if you think that your intellect has taken a nosedive lately, this is the right time to maybe learn calculus, a new language, or enough economics to figure out why the world is in such a deep financial mess.

“If you watch TV, read magazines or surf the Web, you have probably encountered advertisements urging you to exercise your mind. Various brain fitness programs encourage people to stay mentally limber by giving their brain a daily workout—doing everything from memorizing lists and solving puzzles to estimating the number of trees in Central Park.

“It sounds a bit gimmicky, but such programs may have a real basis in neurobiology. Recent work, albeit mostly in rats, indicates that learning enhances the survival of new neurons in the adult brain. And the more engaging and challenging the problem, the greater the number of neurons that stick around. These neurons are then presumably available to aid in situations that tax the mind. It seems, then, that a mental workout can buff up the brain, much as physical exercise builds up the body.

“The findings may be particularly interesting to intellectual couch potatoes whose brains could benefit from a few cerebral sit-ups. More important, though, the results lend some support to the notion that people who are in the early stages of Alzheimer’s disease or who have other forms of dementia might slow their cog­nitive decline by keeping their minds actively engaged.”

Read the rest of the story on Scientific American.