When it comes to understanding the link between healthy aging and hobbies that provide physical, social, and psychological wellness, Americans can thank the good citizens of the Kungsholmen district of Stockholm, Sweden.

That’s because data from The Kungsholmen Project, run by Stockholm’s Karolinksa Institute, has provided researchers with ample evidence that adults who stay mentally active, socially engaged, and physically fit age better and are better protected against age-related dementia, such as Alzheimer’s disease.

The Kungsholmen Project is a longitudinal population-based study of aging and health in which all persons in the district born before 1913 were invited to participate. A total of 2,368 persons have done so. The project so far has contributed data to more than 26 doctoral theses on aging and hundreds of scholarly articles.

One of these articles, called “Mental, Physical, and Social Components in Common Leisure Activities in Old Age in Relation to Dementia,” was published in the journal Neurobiology of Aging. It concludes that leisure activities that have either mentally, physically, or socially stimulating components offer some protection against developing dementia. However, activities such as music making, which combine all three components, offer the greatest benefit.

It’s common knowledge that a proper exercise regimen can do wonders for the body. Only recently, however, have psychologists and gerontologists aggressively applied the same principle to the brain.

Among people who work with older adults, the concept of “cognitive fitness” has become a buzz phrase to describe activities that stimulate areas of the brain and help improve memory. Proponents of brain-fitness exercises say such mental conditioning can help prevent or delay memory loss and the onset of other age-related cognitive disorders.

“The brain is the central processor of the body, and most people don’t do much to keep it as fit as possible,” says Patti Celori, executive director of the New England Cognitive Center. The NECC runs a program to work with older adults to improve cognition. Its activities include computer programs designed to stimulate specific areas of the brain and the replication of geometric designs with pegs and rubber bands. Similar programs include Maintain Your Brain, initiated by the Alzheimer’s Association, and Mind Alert, run by the American Society on Aging.

But any hobby or activity that challenges the brain will help, say psychologists, including doing crossword puzzles and brain teasers, mental arithmetic and memory puzzles, or learning a new skill. One purpose of mental exercise is to reinforce the idea that “in aging, not everything is downhill,” explains Elkhonon Goldberg, a Manhattan neuropsychologist and author of The Wisdom Paradox, a book that examines how some people grow wiser with age.

New findings by the US National Institute for Occupational Safety and Health show that there are significant differences between the hearing abilities of people from different ethnic backgrounds as well as between men and women.

Specifically, people of African decent hear better than people of European decent, and women hear better than men, the government study finds.

Some scientists believe that higher melanin levels in people of African decent may play a role in how the body removes harmful chemical compounds caused by damage to sensitive hair cells in the inner ear. Thus people with higher melanin content in their skin may be protected from noise-induced hearing loss as they age.

The reason why women hear better than men is not well understood at this stage. Elliott Berger, an Indianapolis-based hearing protection expert, said that genetics or differences in noise exposure may explain the difference between women and men. “Boys have typically done noisier activities,” Berger told the Associated Press, which reported on the study’s findings.

The study looked at more than 5,000 people who underwent hearing tests from 1999 through 2004 as part of a comprehensive, annual federal health survey that included physical examinations. The 10- to 20-minute test involved wearing headphones and pressing a button when a tone was heard.

Third, key-mood associations were shown to be invalid for the modern, equal temperament keyboard. Participants showed no ability to be able to identify mood from key or key from mood and, overall, there was no change in perceived mood of a piece if it was performed in a different key.

The authors suggest that the myth has been perpetuated by musical commentators repeating the assumption for the past 200 years. In addition, they say, there are a number of aspects of early musical training which encourage these associations for the sharp and flat keys.

Dr. Robert Zatorre, a psychologist and cognitive neuroscientist at McGill University’s Montreal Neurologist Institute in Canada, has discovered a new way to understand the science behind the brain’s response to music and language. It appears it’s a left brain/right brain thing.

Evidence shows that the left hemisphere of the brain is responsible for processing speech, while the right hemisphere processes music. Some researchers believe that the two parts of the brain process language and music separately since humans make such an exact distinction between whether or not what they are hearing is speech or music.

Zatorre explains that the brain uses both hemispheres as a way to more efficiently handle interpretation of the complex world. For instance, timing is a crucial part of speech, given how fast some humans talk. But while timing is important in music, pitch is a more crucial element. Zatorre believes it is impossible for our brains to comprehend both ways of processing audible information, so the right and left parts of the brain divide the work.

Sergei Prokofiev, that is. Tufts-New England Medical Center researchers say that music in the recovery room cuts the need for post-op pain drugs such as morphine.

The study, by a team led by Dr. M. Soledad Cepeda, a professor at Javeriana University School of Medicine in Bogota, Colombia, and a faculty member of the anesthesia department at Tufts-New England Medical Center, was based on the combined results from 14 studies in which 489 surgery patients listened to prerecorded music.

The researchers found that not only did listening to music reduce the patients’ need for morphine-like drugs, but that patients who listened to music after surgery reported less pain than other patients who were not exposed to it.

For people who have lived through a serious accident, rehabilitation can be slow, painful, and tiring. Rehabilitation therapists often turn to music making as a way to help their patients work longer, harder, and keep their spirits up.

Eighteen-year-old Melissa Wilson of Georgia survived a driving accident, when a dump truck hit her car. Much of Wilson’s left side was shattered, including her hip, leg, pelvis, and foot.

“She’s in a lot of pain,” says Beth Collier, a music therapist at Children’s Healthcare of Atlanta, Georgia. “She needed to strengthen her upper body, because she is going to be using a wheelchair for quite a while.”

To regain her strength, Wilson started working out by playing the drums and other percussion instruments. Collier asks Wilson to play a tambourine in positions over her head, or to her side. Of course, Wilson could work out in a gym, but playing music is far more fun, and it distracts her from the pain.

“I can move the drum to work her left hand, and move it up higher and higher and higher, and she’s worked out that hand and not even thinking twice about it,” Collier explains. “It’s like a vacation from a bad situation,” agrees Wilson.